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{{Short description|1918–1920 global influenza pandemic}}
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{{About|the influenza pandemic that began in 1918|the virus that caused the pandemic|Influenza A virus subtype H1N1}}
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{{Infobox pandemic
| name            = Spanish flu
| image           = Emergency hospital during Influenza epidemic, Camp Funston, Kansas - NCP 1603.jpg
| alt             = Soldiers from Fort Riley, Kansas, ill with Spanish flu at a hospital ward at Camp Funston
| caption         = Soldiers sick with Spanish flu at a hospital ward at [[Camp Funston]] in [[Fort Riley]], Kansas
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| disease         = [[Influenza]]
| virus_strain    = Strains of [[Influenza A virus subtype H1N1|A/H1N1]]
| location        = Worldwide
| date            = February 1918 – April 1920<ref name="NIH-NYC"/>
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| suspected_cases = 500 million (estimated){{sfn|Taubenberger|Morens|2006}}
| deaths          = 25–50 million (generally accepted), other estimates range from 17 to 100 million<ref>{{cite web|date=2013|title=Pandemic Influenza Risk Management WHO Interim Guidance|url=https://www.who.int/influenza/preparedness/pandemic/GIP_PandemicInfluenzaRiskManagementInterimGuidance_Jun2013.pdf?ua=1|url-status=live|archive-url=https://web.archive.org/web/20210121225326/https://www.who.int/influenza/preparedness/pandemic/GIP_PandemicInfluenzaRiskManagementInterimGuidance_Jun2013.pdf?ua=1|archive-date=21 January 2021|access-date=21 August 2021|website=[[World Health Organization]]|page=25}}</ref><ref name="pmid30202996"/><ref>{{cite news |title=History's deadliest pandemics, from ancient Rome to modern America |url=https://www.washingtonpost.com/graphics/2020/local/retropolis/coronavirus-deadliest-pandemics/ |date=7 April 2020 |access-date=11 April 2020 | vauthors = Rosenwald MS |newspaper=[[The Washington Post]] |url-status=live |url-access=subscription |archive-url= https://web.archive.org/web/20200407204000/https://www.washingtonpost.com/graphics/2020/local/retropolis/coronavirus-deadliest-pandemics/ |archive-date=7 April 2020}}</ref>
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{{flu|expanded=pandemics}}
The '''1918–1920 flu pandemic''', also known as the '''Great Influenza epidemic''' or by the common [[misnomer]] '''Spanish flu''', was an exceptionally deadly global [[influenza pandemic]] caused by the [[Influenza A virus subtype H1N1|H1N1]] subtype of the [[influenza A virus]]. The earliest documented case was March 1918 in [[Kansas]], United States, with further cases recorded in [[French Third Republic|France]], [[German Empire|Germany]] and the [[United Kingdom of Great Britain and Ireland|United Kingdom]] in April. Two years later, nearly a third of the global population, or an estimated 500 million people, had been infected. Estimates of deaths range from 17 million to 50 million,<ref>{{Cite web |last=CDC |date=2019-12-17 |title=The Discovery and Reconstruction of the 1918 Pandemic Virus |url=https://www.cdc.gov/flu/pandemic-resources/reconstruction-1918-virus.html |access-date=2022-09-19 |website=Centers for Disease Control and Prevention |language=en-us |archive-date=25 March 2020 |archive-url=https://web.archive.org/web/20200325201749/https://www.cdc.gov/flu/pandemic-resources/reconstruction-1918-virus.html |url-status=live }}</ref><ref>{{Cite journal |last=Spreeuwenberg |date=2018-09-07 |title=Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic |url=https://ourworldindata.org/spanish-flu-largest-influenza-pandemic-in-history |access-date=2024-09-17 |journal=Our World in Data |volume=187 |issue=12 |pages=2561–2567 |doi=10.1093/aje/kwy191 |pmid=30202996 |pmc=7314216 |language=en-us |archive-date=7 September 2021 |archive-url=https://web.archive.org/web/20210907022931/https://ourworldindata.org/spanish-flu-largest-influenza-pandemic-in-history |url-status=live }}</ref> and possibly as high as 100 million,<ref name=":1">{{Cite book | vauthors = Barry JM |author-link=John M. Barry |title=The Great Influenza: The Story of the Deadliest Pandemic in History |title-link=The Great Influenza |publisher=[[Penguin Books]] |year=2021 |isbn=978-0-14-303649-4 |location= |pages=397–398}}</ref> making it [[List of epidemics and pandemics|the deadliest pandemic in history]].

The pandemic broke out near the end of [[World War I]], when wartime [[Censorship|censors]] in the [[belligerent]] countries suppressed bad news to maintain [[morale]], but newspapers [[Freedom of the press|freely reported]] the outbreak in [[Spain during World War I|neutral Spain]], creating a false impression of Spain as the epicenter and leading to the "Spanish flu" misnomer.<ref name=Friday/> Limited historical [[epidemiological]] data make the pandemic's geographic origin indeterminate, with competing hypotheses on the initial spread.{{sfn|Taubenberger|Morens|2006}}

Most influenza outbreaks disproportionately kill the young and old, but this pandemic had unusually high mortality for young adults.{{Sfn|Gagnon|Miller|et al|2013|page=e69586}} Scientists offer several explanations for the high mortality, including a six-year climate anomaly affecting migration of [[disease vectors]] with increased likelihood of spread through bodies of water.<ref name="The Impact of a Six‐Year Climate An">{{cite journal | vauthors = More AF, Loveluck CP, Clifford H, Handley MJ, Korotkikh EV, Kurbatov AV, McCormick M, Mayewski PA | title = The Impact of a Six-Year Climate Anomaly on the "Spanish Flu" Pandemic and WWI | journal = GeoHealth | volume = 4 | issue = 9 | pages = e2020GH000277 | date = September 2020 | pmid = 33005839 | pmc = 7513628 | doi = 10.1029/2020GH000277 | bibcode = 2020GHeal...4..277M | doi-access = free | issn=2471-1403 }}</ref> However, the claim that young adults had a high mortality during the pandemic has been contested.<ref>{{Cite web |vauthors=Marshall L |date=2023-10-09 |title=1918 flu pandemic myth debunked by skeletal remains |url=https://www.colorado.edu/today/2023/10/09/1918-flu-pandemic-myth-debunked-skeletal-remains |access-date=2024-03-26 |website=CU Boulder Today |language=en |archive-date=26 March 2024 |archive-url=https://web.archive.org/web/20240326042156/https://www.colorado.edu/today/2023/10/09/1918-flu-pandemic-myth-debunked-skeletal-remains |url-status=live }}</ref> Malnourishment, overcrowded medical camps and hospitals, and poor [[hygiene]], exacerbated by the war, promoted bacterial [[superinfection]], killing most of the victims after a typically prolonged death bed.<ref name=Brundage>{{cite journal | vauthors = Brundage JF, Shanks GD | title = What really happened during the 1918 influenza pandemic? The importance of bacterial secondary infections | journal = The Journal of Infectious Diseases | volume = 196 | issue = 11 | pages = 1717–18; author reply 1718–19 | date = December 2007 | pmid = 18008258 | doi = 10.1086/522355 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Morens DM, Fauci AS | title = The 1918 influenza pandemic: insights for the 21st century | journal = The Journal of Infectious Diseases | volume = 195 | issue = 7 | pages = 1018–1028 | date = April 2007 | pmid = 17330793 | doi = 10.1086/511989 | doi-access = free }}</ref>

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==Etymologies==
<!--This section should focus on specific terms for this pandemic so it doesn't become a "list of generic terms for flu." Pre-existing names should only be mentioned in the context of explaining new names.-->
[[File:El Sol 28 de mayo de 1918.jpg|thumb|''[[El Sol (Madrid)|El Sol]]'' ([[Madrid]]), 28 May 1918: "The three-day fever – In Madrid 80,000 Are Infected – [[Majesty|H.M.]] [[Alfonso XIII|the King]] is sick"]]
This pandemic was known by many different names depending on place, time, and context. The [[etymology]] of alternative names [[Historicism|historicises]] the scourge and its effects on people who would only learn years [[History of virology|later]] that [[virus]]es caused [[influenza]].<ref>{{harvnb|Davis|2013|p=7}}: "In short, although the Spanish flu 'had nothing "Spanish" about it,' from a strictly epidemiological perspective, its discursive link to the Iberian nation is beyond dispute. The importance of narrative for a historically informed appreciation of the epidemic stems from the importance of this discursive link and is tied directly to the scientific uncertainty about the etiological agent of the epidemic;"</ref> The lack of scientific answers led the ''Sierra Leone Weekly News'' ([[Freetown]]) to suggest a [[biblical]] framing in July 1918, using an [[interrogative]] from [[Beshalach|Exodus 16]] in ancient [[Hebrew]]:{{efn|The Israelites asked: "Ma'n Hu?" {?מן הוא} – in English: 'what is it?'<ref>{{Cite web|date=14 March 2018|title=Biblical Hebrew Words and Meaning|url=https://www.hebrewversity.com/word-mannamean-hebrew/|access-date=11 August 2021|website=hebrewversity|quote=in the original Hebrew the people of Israel asked: "Ma'n Hu?" {?מן הוא} – English for 'what is it?' and that is the origin of the name 'manna'}}</ref>}} "One thing is for certain—the doctors are at present flabbergasted; and we suggest that rather than calling the disease influenza they should for the present until they have it in hand, say {{lang|he-Latn|Man hu}}—'What is it?'"<ref>{{harvnb|Spinney|2018|p=65}}: "In Freetown, a newspaper suggested that the disease be called manhu until more was known about it. Manhu, a Hebrew word meaning 'what is it?'</ref><ref>{{Citation|vauthors=Cole F|title=Sierra Leone and World War 1|publisher=[[University of London]], School of Oriental and African Studies|via=ProQuest Dissertations Publishing|date=1994|id=10731720|page=213|url=https://www.proquest.com/openview/961aaf74c07749e4424eb56c91718d8c/|access-date=11 August 2021|quote=local interpretations of the crisis had become deeply reminiscent of the increasing disobedience of the Israelites in the wilderness of Sin. It was therefore urged that the epidemic be called 'Man hu,' (an obvious corruption of "manna") meaning 'what is it?'|archive-date=11 August 2021|archive-url=https://web.archive.org/web/20210811235039/https://www.proquest.com/openview/961aaf74c07749e4424eb56c91718d8c/|url-status=live}}</ref><ref>{{citation|title=Sierra Leone Weekly News |volume= XXXV|number= 1|date= 9 July 1918|page=6}} quoted in Mueller JW (1998), p. 8.</ref>

===Descriptive names===
Outbreaks of [[influenza-like illness]] were documented in 1916–17 at British military hospitals in [[Étaples]], France,<ref>{{Cite journal|vauthors=Hammond JA, Rolland W, Shore TH|date=14 July 1917|title=Purulent Bronchitis|url=https://doi.org/10.1016/S0140-6736(01)56229-7|journal=The Lancet|volume=190|issue=4898|pages=41–46|doi=10.1016/s0140-6736(01)56229-7|issn=0140-6736|archive-date=22 March 2023|access-date=30 July 2021|archive-url=https://web.archive.org/web/20230322035537/https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(01)56229-7/fulltext|url-status=live}} [https://www.statnews.com/wp-content/uploads/2018/12/Hammond.1917.purulent.bronchitis.pdf Alt URL] {{Webarchive|url=https://web.archive.org/web/20190826134026/https://www.statnews.com/wp-content/uploads/2018/12/Hammond.1917.purulent.bronchitis.pdf |date=26 August 2019 }}</ref> and just across the [[English Channel]] at [[Aldershot]], England. Clinical indications in common with the 1918 pandemic included rapid symptom progression to a "dusky" [[heliotrope (color)|heliotrope]] face. <!--The [[German language|German]] name '{{lang|de|Blitzkatarrh}}' (lightning cold, from {{Langx|grc|καταρρεῖν}}, ''[[Catarrh|katarrhein]]''),<ref name=fes/><ref name=Storey/> captured the sudden onset, while--> This characteristic blue-violet [[cyanosis]] in expiring patients led to the name 'purple death'.<ref>{{cite journal | vauthors = Radusin M | title = The Spanish flu – Part I: the first wave | journal = Vojnosanitetski Pregled | volume = 69 | issue = 9 | pages = 812–817 | date = September 2012 | pmid = 23050410 | url = https://pubmed.ncbi.nlm.nih.gov/23050410 | quote = the Purple Death ... name resulted from the specific skin colour in the most severe cases of the diseased, who by the rule also succumbed to the disease, and is also at the same time the only one which does not link this disease with the Iberian peninsula. This name is actually the most correct. | archive-date = 8 November 2022 | access-date = 31 July 2021 | archive-url = https://web.archive.org/web/20221108114434/https://pubmed.ncbi.nlm.nih.gov/23050410/ | url-status = live }}</ref><ref>{{cite journal | vauthors = McCord CP | title = The Purple Death. Some things remembered about the influenza epidemic of 1918 at one army camp | journal = Journal of Occupational Medicine | volume = 8 | issue = 11 | pages = 593–598 | date = November 1966 | pmid = 5334191 | url = https://pubmed.ncbi.nlm.nih.gov/5334191 | publisher = Industrial Medical Association | archive-date = 8 November 2022 | access-date = 31 July 2021 | archive-url = https://web.archive.org/web/20221108114434/https://pubmed.ncbi.nlm.nih.gov/5334191/ | url-status = live }}</ref><ref>{{Cite book|vauthors=Getz D|url=http://worldcat.org/oclc/1006711971|title=Purple death : the mysterious Spanish flu of 1918|year=2017|publisher=Square Fish|isbn=978-1-250-13909-2|oclc=1006711971|archive-date=22 March 2023|access-date=31 July 2021|archive-url=https://web.archive.org/web/20230322035537/https://worldcat.org/title/1006711971|url-status=live}}</ref>

The Aldershot physicians later wrote in ''[[The Lancet]]'', "the influenza pneumococcal purulent bronchitis we and others described in 1916 and 1917 is fundamentally the same condition as the influenza of this present pandemic."<ref name=Oxford>{{cite journal | vauthors = Oxford JS, Gill D | title = A possible European origin of the Spanish influenza and the first attempts to reduce mortality to combat superinfecting bacteria: an opinion from a virologist and a military historian | journal = Human Vaccines & Immunotherapeutics | volume = 15 | issue = 9 | pages = 2009–2012 | date = 2 September 2019 | pmid = 31121112 | pmc = 6773402 | doi = 10.1080/21645515.2019.1607711 | quote = Two papers were published in The Lancet in 1917 describing an outbreak of disease constituting 'almost a small epidemic'. The first paper was written by physicians at a hospital center in northern France,3 and the second by a team at an army hospital in Aldershot, in southern England. In both earlier instances and in the 1918 pandemic the disease was characterized by a 'dusky' cyanosis, a rapid progression from quite minor symptoms to death }}</ref> This "[[purulent]] [[bronchitis]]" <!--({{langx|la|purulentus, full of pus}}) -->is not yet linked to the same [[Influenza A virus subtype H1N1|A/H1N1]] virus,<ref name=Cox/> but it may be a precursor.<ref name=Oxford/><ref>{{cite journal | vauthors = Honigsbaum M | title = Spanish influenza redux: revisiting the mother of all pandemics | journal = Lancet | volume = 391 | issue = 10139 | pages = 2492–2495 | date = June 2018 | pmid = 29976462 | doi = 10.1016/S0140-6736(18)31360-6 | quote = Labelled 'purulent bronchitis' for want of a better term, the disease proved fatal in half the cases and many soldiers also developed cyanosis. 2 years later, British respiratory experts, also writing in The Lancet, but this time in the wake of the pandemic, would decide the disease had been 'fundamentally the same condition' as 'Spanish' influenza | s2cid = 49709093 }}</ref><ref>{{cite journal | vauthors = Dennis Shanks G, Mackenzie A, Waller M, Brundage JF | title = Relationship between "purulent bronchitis" in military populations in Europe prior to 1918 and the 1918–1919 influenza pandemic | journal = Influenza and Other Respiratory Viruses | volume = 6 | issue = 4 | pages = 235–239 | date = July 2012 | pmid = 22118532 | pmc = 5779808 | doi = 10.1111/j.1750-2659.2011.00309.x }}</ref>

In 1918, 'epidemic [[influenza]]',<ref name=Storey>{{Cite news|date=21 September 2020|vauthors=Storey, C|title=OLD NEWS: Influenza was an old foe long before 1918|url=https://www.arkansasonline.com/news/2020/sep/21/flu-outbreaks-didnt-start-in-1918/|access-date=7 August 2021|series=Opinion|work=[[Arkansas Democrat-Gazette]]|quote=I came across this seemingly astute analysis in the Dec. 21, 1913, Gazette.... It was a 'Special Cable to the Gazette Through the International News Service.' ''Grip Is a Disease Without a Country; All Nations Repudiate Malady: Each Blaming Other Kingdoms,'' London, Dec. 20. — The grip is a disease without a country, according to a new book just issued which is devoted to the malady. Every country tries to make it out a native of another land.... Eighteenth-century Italian writers say Dr. Hopkirk spoke of "una influenza di freddo" (influence of cold), and English physicians, mistaking the word influenza for the name of the disease itself, used it. The same term is also used in Germany, where a host of dialect names still prevail, such as lightning catarrh and fog plague.|archive-date=7 August 2021|archive-url=https://web.archive.org/web/20210807155738/https://www.arkansasonline.com/news/2020/sep/21/flu-outbreaks-didnt-start-in-1918/|url-status=live}}</ref> also known at the time as 'the grip' ({{langx|fr|la grippe}}, grasp),<ref name=Grippe>{{Cite news|title=Grippe is not new|work=[[Los Angeles Herald]]|date=14 January 1899|at=p. 6 col. 6|via=California Digital Newspaper Collection|url=https://cdnc.ucr.edu/?a=d&d=LAH18990114.2.131&e=-------en--20--1--txt-txIN--------1|access-date=7 August 2021|quote=French doctors gave it the name of "la grippe," which is now anglicized into "the grip" ... It is known all over the world, and there is a disposition in every nation to shift the odium of it upon some other country. Then the Russians call it the Chinese catarrh, the Germans often call it the Russian pest, the Italians name it the German disease, and the French call it sometimes the Italian fever and sometimes the Spanish catarrh.|archive-date=7 August 2021|archive-url=https://web.archive.org/web/20210807205532/https://cdnc.ucr.edu/?a=d&d=LAH18990114.2.131&e=-------en--20--1--txt-txIN--------1|url-status=live}}</ref> appeared in [[Kansas]], U.S., during late spring, and early reports from [[Spain]] began appearing on 21 May.<ref>{{harvnb|Davis|2013|p=27}}: "On May 21, 1918, ''El Liberal'' published a scant article titled 'Can One Live? The Fashionable Illness.' Likely the first account in Spain of the Spanish flu, it begins: 'For several days, Madrid has been affected by an epidemic, which fortunately is mild; but which, from what it appears, intends to kill doctors from overwork'.... The following day, ''El Sol'' and ''ABC'' published their first stories about the epidemic: 'What is the Cause? An Epidemic in Madrid' and 'Benign Epidemic. The Sickbay in Madrid,' respectively."</ref><ref>{{Cite web|vauthors=Alfeirán X|date=7 December 2015|title=La fiebre de los tres días|trans-title=The three-day fever|url=https://www.lavozdegalicia.es/noticia/coruna/coruna/2015/12/07/fiebre-tres-dias/0003_201512H7C6991.htm|access-date=29 July 2021|website=La Voz de Galicia|location=[[A Coruña]]|language=es|quote=Las primeras noticias aparecieron en la prensa de Madrid el 21 de mayo de 1918.|trans-quote=The first news appeared in the press of Madrid on 21 May 1918.|archive-date=29 July 2021|archive-url=https://web.archive.org/web/20210729031647/https://www.lavozdegalicia.es/noticia/coruna/coruna/2015/12/07/fiebre-tres-dias/0003_201512H7C6991.htm|url-status=live}}</ref> Reports from both places called it 'three-day fever'.<ref>{{Cite news|vauthors=McClure J|title=Spanish flu of 1918 no three-day fever. Try 365-day worldwide plague|url=https://www.ydr.com/story/news/history/blogs/york-town-square/2009/05/01/currentflu/31647929/|access-date=29 July 2021|work=[[York Daily Record]]|date=1 May 2009|archive-date=29 July 2021|archive-url=https://web.archive.org/web/20210729031637/https://www.ydr.com/story/news/history/blogs/york-town-square/2009/05/01/currentflu/31647929/|url-status=live}}</ref><ref>{{Cite news|vauthors=Calleja S|date=29 July 2021|title=La fiebre de los tres días|trans-title=The three-day fever|url=https://www.diariodeleon.es/articulo/provincia/la-fiebre-de-los-tres-dias/201810211246001802480.html|access-date=21 October 2018|work=[[Diario de León]]|location=[[León, Spain]]|language=es|archive-date=29 July 2021|archive-url=https://web.archive.org/web/20210729031636/https://www.diariodeleon.es/articulo/provincia/la-fiebre-de-los-tres-dias/201810211246001802480.html|url-status=live}}</ref><ref>{{Cite web|title=Impacto de la gripe de 1918 en España|url=https://vacunasaep.org/profesionales/noticias/gripe-espanola-1918-parte2|access-date=29 July 2021|website=Comité Asesor de Vacunas de la Asociación Española de Pediatría|trans-website=Vaccine Advisory Committee of the Spanish Association of Pediatrics|language=es|quote=En España, se le llamó al principio 'la fiebre de los tres días', atendiendo a la creencia, como en otros países, de que la gripe era una enfermedad leve. Las primeras noticias sobre la gripe, llamando la atención sobre que algo distinto estaba ocurriendo, aparecieron en la prensa a finales de mayo. Por ej. en el diario ABC el 22 de mayo mediante una escueta nota en la página 24: 'Los médicos han comprobado, en Madrid, la existencia de una epidemia de índole gripal, muy propagada, pero, por fortuna, de carácter leve'.|trans-quote=In Spain, it was initially called 'the three-day fever', based on the belief, as in other countries, that the flu was a mild illness. The first reports about the flu, drawing attention to the fact that something different was happening, appeared in the press at the end of May. For example, in the newspaper ABC on 22 May, through a brief note on page 24: "The doctors have verified, in Madrid, the existence of an epidemic of a influenza nature, very widespread, but, fortunately, of a mild nature.'|archive-date=29 July 2021|archive-url=https://web.archive.org/web/20210729031647/https://vacunasaep.org/profesionales/noticias/gripe-espanola-1918-parte2|url-status=live}}</ref>

===Associative names===
Many alternative names are [[exonyms]] in the practice of making new [[Infection|infectious diseases]] seem foreign.<ref>{{Cite book|vauthors=Killingray D, Phillips H|url=https://books.google.com/books?id=k79_8QX8n44C|title=The Spanish Influenza Pandemic of 1918–1919: New Perspectives|year=2003|publisher=Routledge|isbn=978-1-134-56640-2|quote=In the popular mind calamities often need to have their origin and cause identified and other countries or peoples credited with blame. This xenophobic response has been common in Europe, that impulse to blame others or the silent places of the Asian heartlands for the source of disease.|archive-date=1 October 2024|access-date=3 May 2020|archive-url=https://web.archive.org/web/20241001014330/https://books.google.com/books?id=k79_8QX8n44C|url-status=live}}</ref><ref name=Hoppe>{{cite journal | vauthors = Hoppe T | title = "Spanish Flu": When Infectious Disease Names Blur Origins and Stigmatize Those Infected | journal = American Journal of Public Health | volume = 108 | issue = 11 | pages = 1462–1464 | date = November 2018 | pmid = 30252513 | pmc = 6187801 | doi = 10.2105/AJPH.2018.304645 }}</ref><ref name="Müller"/> This pattern was observed even before the [[1889–1890 pandemic]], also known as the 'Russian flu', when the Russians already called epidemic influenza the 'Chinese catarrh', the Germans called it the 'Russian pest', and the Italians called it the 'German disease'.<ref>{{Cite book|vauthors=Reynolds JR|url=https://books.google.com/books?id=XOBDAQAAMAAJ&q=the+Germans+,+the+Russian+pest&pg=PA31|title=A System of Medicine|date=1866|volume=1|pages=30–31|publisher=Macmillan|quote=One is, that every epidemic owns one unknown source, whence it spreads; each nation, in turn, attributing to its neighbour from whom it derived the disease, the unenviable honour of originating it. Thus the Italians have termed it the German disease; the Germans, the Russian pest; the Russians, the Chinese Catarrh;|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014332/https://books.google.com/books?id=XOBDAQAAMAAJ&q=the+Germans+,+the+Russian+pest&pg=PA31#v=snippet&q=the%20Germans%20%2C%20the%20Russian%20pest&f=false|url-status=live}}</ref><ref>{{Cite journal |title=Editorials: La Grippe |url=https://books.google.com/books?id=87tXAAAAMAAJ&q=%22Like+every+other+disease+about+whose+pathology+we+know+very+little,%22&pg=PA217 |journal=Gaillard's Medical Journal |date=January 1890 |veditors=Harrison MA, Claiborne JH Jr |volume=50 |page=217 |quote=The outbreak immediately preceding the present one was in 1879, and has been well described by Da Costa. Like every other disease about whose pathology we know very little, this malady has not a scientifically correct name, but at different times and in different countries has received names which are almost purely local; thus the Russians have called it the Chinese catarrh, because it has often invaded Russia from China. The Germans call it the Russian pest, while the Italians in turn call it the German disease. |archive-date=1 October 2024 |access-date=3 August 2021 |archive-url=https://web.archive.org/web/20241001014341/https://books.google.com/books?id=87tXAAAAMAAJ&q=%22Like+every+other+disease+about+whose+pathology+we+know+very+little,%22&pg=PA217#v=snippet&q=%22Like%20every%20other%20disease%20about%20whose%20pathology%20we%20know%20very%20little%2C%22&f=false |url-status=live }}</ref> These [[epithet]]s were re-used in the 1918 pandemic, along with new ones.<ref name=Davis/>

===='Spanish' influenza====
[[File:The Times 1918-06-28 p8.jpg|thumb|right|upright=1.0|Advertisement in ''[[The Times]]'', 28 June 1918 for Formamint tablets to prevent "Spanish influenza"]]
Outside Spain, the disease was soon misnamed 'Spanish influenza'.{{sfn|Porras-Gallo|Davis|2014|p=51}}{{sfn|Galvin|2007}} In a 2 June 1918 ''[[The Times]]'' of [[London]] dispatch titled, "The Spanish Epidemic," a correspondent in [[Madrid]] reported over 100,000 victims of, "The unknown disease...clearly of a gripal character," without referring to "Spanish influenza" directly.<ref>{{Cite news|date=2 June 1918|title=The Spanish Epidemic|work=[[The Times]]|location=London|url=https://www.thetimes.com/tto/archive/article/1918-06-03/5/10.html|access-date=29 July 2021|quote=The unknown disease which appeared in Madrid a fortnight ago spread with remarkable rapidity.... It is reported that there are well over 100,000 victims in Madrid alone.... Although the disease is clearly of a gripal character...|archive-date=21 January 2025|archive-url=https://web.archive.org/web/20250121111514/https://www.thetimes.com/tto/archive/article/1918-06-03/5/10.html|url-status=live}}</ref> Three weeks later <!--on June 25,--> ''The Times'' reported that, "Everybody thinks of it as the 'Spanish' influenza to-day."<ref>{{Cite news|date=25 June 1918|title=The Spanish Influenza; A Sufferer's Symptoms.|work=[[The Times]]|location=London|url=https://www.thetimes.com/tto/archive/article/1918-06-25/9/16.html|access-date=29 July 2021|archive-date=21 January 2025|archive-url=https://web.archive.org/web/20250121111531/https://www.thetimes.com/tto/archive/article/1918-06-25/9/16.html|url-status=live}}</ref> Three days after that an advertisement appeared in ''The Times'' for Formamint tablets to prevent "Spanish influenza".<ref>{{Cite news|date=28 June 1918|title=Public Notice; 'Spanish Influenza' Epidemic|work=[[The Times]] |location=London| url=https://www.thetimes.com/tto/archive/article/1918-06-28/8/4.html| access-date=11 August 2021}}</ref><ref>{{Cite web|title=Eat More Onions!|date=13 September 2018|vauthors=Arnold C|url=https://www.laphamsquarterly.org/roundtable/eat-more-onions|access-date=12 August 2021|website=Lapham's Quarterly|language=en|quote=daily newspapers carried an increasing number of advertisements for influenza-related remedies as drug companies played on the anxieties of readers and reaped the benefits. From the Times of London to the Washington Post, page after page was filled with dozens of advertisements for preventive measures and over-the-counter remedies. 'Influenza!' proclaimed an advert extolling the virtues of Formamint lozenges.|archive-date=12 August 2021|archive-url=https://web.archive.org/web/20210812120222/https://www.laphamsquarterly.org/roundtable/eat-more-onions|url-status=live}}</ref> When it reached Moscow, ''[[Pravda]]'' announced, "{{lang|ru-Latn|Ispánka}} (the Spanish lady) is in town," making 'the Spanish lady' another common name.<ref>{{Cite web|date=29 April 2018|vauthors=Daniels R|title=In Search of an Enigma: The "Spanish Lady"|url=http://www.historyofnimr.org.uk:80/mill-hill-essays/essays-yearly-volumes/1998-2/in-search-of-an-enigma-the-spanish-lady/|archive-url=https://web.archive.org/web/20180429101734/http://www.historyofnimr.org.uk/mill-hill-essays/essays-yearly-volumes/1998-2/in-search-of-an-enigma-the-spanish-lady/|archive-date=29 April 2018|access-date=9 August 2021|website=NIMR History|via=web.archive.org|orig-date=1998 Mill Hill Essays|quote=In turn, when Russia reported on the situation in Moscow, Pravda printed "Ispanka (The Spanish Lady) is in town" and the name has stuck.|url-status=live}}</ref>

The outbreak did not originate in Spain,<ref name=Spain>{{cite journal | vauthors = Trilla A, Trilla G, Daer C | title = The 1918 "Spanish flu" in Spain | journal = Clinical Infectious Diseases | volume = 47 | issue = 5 | pages = 668–673 | date = September 2008 | pmid = 18652556 | doi = 10.1086/590567 }}</ref> but reporting did, due to wartime [[censorship]] in [[belligerent]] nations. Spain was a [[neutral country]] unconcerned with appearances of [[combat readiness]], and without a [[Propaganda#Wartime|wartime propaganda]] machine to prop up [[morale]],<ref>{{cite news |archive-url=https://web.archive.org/web/20100127100727/http://www.channel4.com/news/articles/world/spanish%20flu%20facts/111285 |archive-date=27 January 2010 |url=http://www.channel4.com/news/articles/world/spanish%20flu%20facts/111285 |website=Channel&nbsp;4 News |title=Spanish flu facts}}</ref><ref>{{cite web | vauthors = Anderson S |title=Analysis of Spanish flu cases in 1918–1920 suggests transfusions might help in bird flu pandemic |url=http://www.eurekalert.org/pub_releases/2006-08/acop-aos082806.php |publisher=[[American College of Physicians]] |access-date=2 October 2011 |date=29 August 2006 |archive-url= https://web.archive.org/web/20111125222223/http://www.eurekalert.org/pub_releases/2006-08/acop-aos082806.php |archive-date=25 November 2011 |url-status=live}}</ref> so its newspapers [[freedom of the press|freely]] reported epidemic effects, making Spain the apparent locus of the epidemic.{{sfn|Barry|2004|p=171}} The censorship was so effective that Spain's health officials were unaware its neighboring countries were similarly affected.<ref name=Economist>{{Cite news|title=The centenary of the 20th century's worst catastrophe|vauthors=Spinney L|newspaper=The Economist|url=https://www.economist.com/science-and-technology/2018/09/29/the-centenary-of-the-20th-centurys-worst-catastrophe|date=29 September 2018b|access-date=3 August 2021|issn=0013-0613|quote=On June 29th 1918 Martín Salazar, Spain's inspector-general of health, stood up in front of the Royal Academy of Medicine in Madrid. He declared, not without embarrassment, that the disease which was ravaging his country was to be found nowhere else in Europe. In fact, that was not true. The illness in question, influenza, had been sowing misery in France and Britain for weeks, and in America for longer, but Salazar did not know this because the governments of those countries, a group then at war with Germany and its allies, had made strenuous efforts to suppress such potentially morale-damaging news.|archive-date=3 August 2021|archive-url=https://web.archive.org/web/20210803021036/https://www.economist.com/science-and-technology/2018/09/29/the-centenary-of-the-20th-centurys-worst-catastrophe|url-status=live}}</ref> In an October 1918 "Madrid Letter" to the ''[[Journal of the American Medical Association]]'', a Spanish official protested, "we were surprised to learn that the disease was making ravages in other countries, and that people there were calling it the 'Spanish grip'. And wherefore Spanish? ...this epidemic was not born in Spain, and this should be recorded as a historic vindication."<ref>{{Cite journal|url=https://books.google.com/books?id=iohMAQAAMAAJ&q=%22we+were+surprised+to+learn+that+the+disease+was+making+ravages+in+other+countries+,+and+that+people+there+were+calling+it+the+%22+Spanish+grip+.+%E2%80%9D+And+wherefore+Spanish+&pg=PA1594|title=Madrid Letter|journal=[[Journal of the American Medical Association]]|date=9 November 1918|volume=71|issue=19|page=1594|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014258/https://books.google.com/books?id=iohMAQAAMAAJ&q=%22we+were+surprised+to+learn+that+the+disease+was+making+ravages+in+other+countries+,+and+that+people+there+were+calling+it+the+%22+Spanish+grip+.+%E2%80%9D+And+wherefore+Spanish+&pg=PA1594#v=snippet&q=%22we%20were%20surprised%20to%20learn%20that%20the%20disease%20was%20making%20ravages%20in%20other%20countries%20%2C%20and%20that%20people%20there%20were%20calling%20it%20the%20%22%20Spanish%20grip%20.%20%E2%80%9D%20And%20wherefore%20Spanish&f=false|url-status=live}}</ref>

[[File:The Times 1918-06-25.jpg|thumb|left|upright=1.0|Front page of ''[[The Times]]'' ([[London]]), 25 June 1918: "The Spanish Influenza"]]

====Other exonyms====
French press initially used 'American flu', but adopted 'Spanish flu' in lieu of antagonizing an ally.<ref name=fiction>{{cite journal | vauthors = Vázquez-Espinosa E, Laganà C, Vázquez F | title = The Spanish flu and the fiction literature | journal = Revista Espanola de Quimioterapia | volume = 33 | issue = 5 | pages = 296–312 | date = October 2020 | pmid = 32633114 | pmc = 7528412 | doi = 10.37201/req/049.2020 | quote = French journalists had, initially, called it the 'American flu'; but the fact that the American soldiers were his allies in the warlike conflict advised not to assign such a link to them.... Another most popular name in Madrid, was the 'Soldado de Nápoles' (Naples soldier), a popular song in the zarzuela (popular musical genre or 'género chico' in Spain) called ''La canción del olvido'' (The forgotten song) due both, were 'highly contagious'. Today, there are many authors who avoid such a name (the Spanish flu) and they aptly refer to it as the '1918- 1819[sic] influenza pandemic' }}</ref> In the spring of 1918, British soldiers called it 'Flanders flu', while German soldiers used '{{lang|de|Flandern-Fieber}}' (Flemish fever), both after a [[Battle of the Lys (1918)|battlefield]] in [[Belgium]] where many soldiers on both sides fell ill.<ref name=Davis>{{Cite book|vauthors=Davis KC|url=https://www.worldcat.org/oclc/1034984776|title=More deadly than war : the hidden history of the Spanish flu and the First World War|date=2018|isbn=978-1-250-14512-3|edition=First|location=New York | publisher = Henry Holt and Company |oclc=1034984776|quote=The Russians called it the Chinese flu. In Japan, it was wrestler's fever. In South Africa, it was known as either the white man's sickness or kaffersiekte blacks' disease. Soldiers fighting in the Great War called it the three-day fever—a highly inaccurate description—and when it first struck in the spring of 1918, German soldiers called it Flanders fever, after one of the war's most notorious and deadly battlefields}}</ref><ref name="Müller">{{Cite journal|vauthors=Bax D|year=2020|issue=13|title=Pandemie – Welt im Fieber|trans-title=Pandemic – World in Fever|url=https://www.freitag.de/autoren/der-freitag/welt-im-fieber|access-date=31 July 2021|newspaper=Der Freitag|language=de|quote=In Großbritannien wurde die Krankheit dagegen als 'Flandrische Grippe' bezeichnet, weil sich viele —en in den Schützengräben von Flandern ansteckten.|trans-quote=In Britain, on the other hand, the disease was called the 'Flanders flu' because many soldiers became infected in the trenches of Flanders.|archive-date=31 July 2021|archive-url=https://web.archive.org/web/20210731023931/https://www.freitag.de/autoren/der-freitag/welt-im-fieber|url-status=live}}</ref><ref name=fes>{{Cite web|title=Spanische Grippe|trans-title=The Spanish Flu|vauthors=Müller S|location=[[Bonn]]|year=2020|url=https://www.fes.de/themenportal-geschichte-kultur-medien-netz/geschichte/spanische-grippe|access-date=31 July 2021|website=www.fes.de|publisher=Friedrich Ebert Foundation|language=de|quote=In Europa wurde die Spanischer Grippe auch als 'Blitzkatarrh', als 'Flandern-Fieber', 'flandische Grippe', bei Engländern und Amerikanern als 'three-day'- oder 'knock-me-down'-Fieber, und in Frankreich als 'la grippe', als 'bronchite purulente' (eitrige Bronchitis) oder beim französische Militärärzte als 'Krankheit 11' (maladie onze) bezeichnet. Die Benennung von Krankheiten und insbesondere Seuchen nach ihrem vermuteten Ursprungsort ist nichts Ungewöhnliches. Es ist der Versuch, einem Geschehen auf die Spur zu kommen. Zugleich werden auf diese Weise Krankheiten als etwas Äußerliches gekennzeichnet, als etwas Fremdes, das eingedrungen ist oder eingeschleppt wurde.|trans-quote=In Europe, the Spanish flu was also referred to as 'Blitzkatarrh', as 'Flanders fever', 'Flanders flu', in English and Americans as 'three-day' or 'knock-me-down' fever, and in France as 'la flu', as 'bronchite purulente' (purulent bronchitis) or by French military doctors as 'disease 11' (maladie onze). The naming of diseases and especially epidemics according to their presumed place of origin is nothing unusual. It is an attempt to track down what is happening. At the same time, in this way, diseases are marked as something external, as something foreign that has invaded or been introduced.|archive-date=31 July 2021|archive-url=https://web.archive.org/web/20210731023932/https://www.fes.de/themenportal-geschichte-kultur-medien-netz/geschichte/spanische-grippe|url-status=live}}</ref><ref name=IRCC>{{Cite web|vauthors=Cotter C|date=23 April 2020|title=From the 'Spanish Flu' to COVID-19: lessons from the 1918 pandemic and First World War|url=https://blogs.icrc.org/law-and-policy/2020/04/23/spanish-flu-covid-19-1918-pandemic-first-world-war/|access-date=7 August 2021|series=Humanitarian Law & Policy|publisher=[[International Committee of the Red Cross]]|quote=Many other nicknames were given to the pandemic, many based on nationality or race: 'Spanish Lady', 'French Flu', 'Naples Soldier', 'Purple Death', 'War Plague', 'Flanders Grippe', 'Kirghiz Disease', 'Black Man's Disease', 'Hun Flu', 'German Plague', 'Bolshevik Disease' or even the 'Turco-Germanic bacterium criminal entreprise'. These discriminatory epithets reflect the many rumors and theories that quickly spread about the origins of the pathology.|archive-date=7 August 2021|archive-url=https://web.archive.org/web/20210807235800/https://blogs.icrc.org/law-and-policy/2020/04/23/spanish-flu-covid-19-1918-pandemic-first-world-war/|url-status=live}}</ref> In [[Senegal]] it was named 'Brazilian flu', and in [[Brazil]], 'German flu'.{{sfn|Spinney|2018|p=58}} In Spain it was also known as the 'French flu' ({{lang|es|gripe francesa}}),<ref name=Spain/><ref name=Friday>{{Cite web|vauthors=Mayer J|title=The Origin Of The Name 'Spanish Flu'|url=https://www.sciencefriday.com/articles/the-origin-of-the-spanish-flu/|date=29 January 2019|access-date=30 July 2021|website=Science Friday|quote=Etymology: In ancient times, before epidemiology science, people believed the stars and "heavenly bodies" flowed into us and dictated our lives and health—influenza means 'to influence' in Italian, and the word stems from the Latin for 'flow in.' Sickness, like other unexplainable events, was attributed to the influence of the stars... But the name for the infamous 1918 outbreak, the Spanish flu, is actually a misnomer.|archive-date=29 January 2019|archive-url=https://web.archive.org/web/20190129222525/https://www.sciencefriday.com/articles/the-origin-of-the-spanish-flu/|url-status=live}}</ref> or the 'Naples Soldier' ({{lang|es|Soldado de Nápoles}}), after a popular song from a [[zarzuela]].{{efn|Then paying in [[Madrid]],''The Song of Forgetting'' ({{lang|es|La canción del olvido}})—because the tune was as catchy as the flu.{{sfn|Davis|2013|pp=103–36}}}}<ref name=fiction/> Spanish flu ({{lang|es|gripe española}}) is now a common name in Spain,<ref>{{cite web | vauthors = Landgrebe P |title=100 Years After: The Name of Death |url=https://historycampus.org/2018/spanish-flu-100-years-—-name-of-the-death/ |publisher=History Campus |access-date=16 August 2020 |date=29 December 2018 |archive-url=https://web.archive.org/web/20200816202544/https://historycampus.org/2018/spanish-flu-100-years-after-name-of-the-death/ |archive-date=16 August 2020 |url-status=live}}</ref> but remains controversial there.<ref name="Rodríguez 2019">{{Cite news|vauthors=Rodríguez LP, Palomba AL|date=5 March 2019|title=How is the adjective 'Spanish' used in other languages?|work=[[El País]]|edition=English|location=[[Madrid]]|url=https://english.elpais.com/elpais/2019/02/19/inenglish/1550570720_431591.html|access-date=1 August 2021|quote=The use of 'Spanish' can often have negative connotations, with the adjective often unfairly used to describe unwelcome events and problems. The most obvious example is the so-called 'Spanish flu,' a reference to the 1918 influenza pandemic...|archive-date=1 August 2021|archive-url=https://web.archive.org/web/20210801144508/https://english.elpais.com/elpais/2019/02/19/inenglish/1550570720_431591.html|url-status=live}}</ref><ref name="CBC 2020">{{cite news | vauthors=O'Reilly T | series=Under the Influence | title=How the Spanish Flu wasn't Spanish at all | work=[[CBC Radio]] | date=13 May 2020 | url=https://www.cbc.ca/radio/undertheinfluence/how-the-spanish-flu-wasn-t-spanish-at-all-1.5607552 | access-date=1 August 2021 | quote=Medical professionals and officials in Spain protested. They said the Spanish people were being falsely stigmatized.... If you've ever wondered about the staying power of a brand, the 'Spanish Flu' is a case in point. A full 100 years later, the 'Spanish Flu' is still referenced — and still remains a source of irritation in Spain. | archive-date=1 August 2021 | archive-url=https://web.archive.org/web/20210801144506/https://www.cbc.ca/radio/undertheinfluence/how-the-spanish-flu-wasn-t-spanish-at-all-1.5607552 | url-status=live }}</ref>

[[Other (philosophy)|Othering]] derived from geopolitical borders and social boundaries.{{Sfn|Dionne|Turkmen|2020}}<ref name="v885">{{cite journal |last1=Ristić |first1=Dušan |last2=Marinković |first2=Dušan |date=2022-11-14 |title=Biopolitics of othering during the COVID-19 pandemic |journal=Humanities and Social Sciences Communications |publisher=Palgrave |volume=9 |issue=1 |page=409 |doi=10.1057/s41599-022-01435-7 |issn=2662-9992 |pmc=9662131 |pmid=36406151 |doi-access=free}}</ref> In Poland it was the '[[Bolshevik]] disease',{{sfn|Spinney|2018|p=58}}<ref name=Takon>{{Cite web|vauthors=Takon L|date=7 April 2020|title=Fighting words: how war metaphors can trigger racism|url=https://lighthouse.mq.edu.au/article/march/Fighting-words-how-war-metaphors-can-trigger-racism|access-date=8 August 2021|website=The Lighthouse|publisher=[[Macquarie University]]|language=en-au|quote=the names given to this disease in different parts of the world reflected prevailing concerns about certain ethnic groups and ideologies. The disease was called the 'Singapore fever' in Penang and the Bolshevik disease in Poland.|archive-date=8 August 2021|archive-url=https://web.archive.org/web/20210808221751/https://lighthouse.mq.edu.au/article/march/Fighting-words-how-war-metaphors-can-trigger-racism|url-status=live}}</ref> while in Russia it was referred to it as the '[[Kyrgyz people|Kirghiz]] disease'.<ref name=IRCC/> Some Africans called it a 'white man's sickness', but in [[South Africa]], white men also used the [[ethnophaulism]] {{lang|af|[[Kaffir (racial term)|'kaffersiekte']]}} ({{lit|[[negro]] disease}}).<ref name=Davis/><ref>{{Cite book|vauthors=Phillips H|url=https://books.google.com/books?id=DktxAAAAMAAJ&q=In+one+area+where+Blacks+were+the+first+victims+,+the+accusatory+term+,+%E2%80%9C+Kaffersiekte+%E2%80%9D+was+coined|title=Black October: The Impact of the Spanish Influenza Epidemic of 1918 on South Africa|date=1990|publisher=Government Printer, South Africa|isbn=978-0-7970-1580-7|language=en|quote=In one area where Blacks were the first victims, the accusatory term  'Kaffersiekte' was coined; in another district, where the position was reversed, Blacks returned the compliment with, White man's sickness'|archive-date=1 October 2024|access-date=12 August 2021|archive-url=https://web.archive.org/web/20241001014333/https://books.google.com/books?id=DktxAAAAMAAJ&q=In+one+area+where+Blacks+were+the+first+victims+,+the+accusatory+term+,+%E2%80%9C+Kaffersiekte+%E2%80%9D+was+coined|url-status=live}}</ref> [[Japan]] blamed [[sumo]] wrestlers for bringing the disease home from [[Taiwan#Japanese rule (1895–1945)|Taiwan]], calling it 'sumo flu' ({{lang|ja-Latn<!--|相撲風邪-->|Sumo Kaze}}).<ref>{{Cite news|script-title=ja:余録: 「春のさきぶれ」といえば何か聞こえが良いが...|trans-title=Speaking of "spring sekibu", something sounds good...|date=15 May 2020|url=https://mainichi.jp/articles/20200515/ddm/001/070/126000c|access-date=8 August 2021|script-work=ja:=毎日新聞|trans-work=Mainichi Shimbun morning newspaper|language=ja|script-quote=ja:翌月の東京の夏場所は高熱などによる全休力士が相次いだ.世間はこれを「相撲風邪」「力士風邪」と呼んだが、実はこの謎の感染症こそが同年初めから米国で流行の始まった「スペイン風邪」とみられている.|trans-quote=The following month, a number of sumo wrestlers were absent from the summer tournament in Tokyo due to high fevers. People called it the "sumo flu" or "wrestler flu," but in fact, this mysterious infection is believed to be the Spanish flu, which began spreading in the United States early that year.|archive-date=8 August 2021|archive-url=https://web.archive.org/web/20210808050339/https://mainichi.jp/articles/20200515/ddm/001/070/126000c|url-status=live}}</ref><ref>{{Cite web|title=How the Spanish flu of 1918-20 ravaged Japan|url=https://japantoday.com/category/features/kuchikomi/how-the-spanish-flu-of-1918-20-ravaged-japan|access-date=8 August 2021|website=Japan Today|date=6 May 2020|language=en|quote=The first patients in Japan, reported Shukan Gendai (May 2–9), began showing symptoms around April 1918. Initially the disease was referred to as the "Sumo Kaze" (sumo cold) because a contingent of sumo wrestlers contracted it while on a tour of Taiwan. Three well known grapplers, Masagoishi, Choshunada and Wakagiyama, died before they could return from Taiwan. As the contagion spread, the summer sumo tournament, which would have been held on the grounds of Yasukuni shrine, was cancelled.|archive-date=8 August 2021|archive-url=https://web.archive.org/web/20210808050338/https://japantoday.com/category/features/kuchikomi/how-the-spanish-flu-of-1918-20-ravaged-japan|url-status=live}}</ref>

[[World Health Organization]] 'best practices' first published in 2015 now aim to prevent [[social stigma]] by not associating [[Cultural heritage|culturally significant]] names with new diseases, listing "Spanish flu" under "examples to be avoided".{{Sfn|Dionne|Turkmen|2020|pp=213–230}}<ref name=Hoppe/><ref>{{Cite web|title=WHO issues best practices for naming new human infectious diseases|url=https://www.who.int/news/item/08-05-2015-who-issues-best-practices-for-naming-new-human-infectious-diseases|date=8 May 2015|access-date=4 August 2021|website=www.who.int|language=en|archive-date=31 July 2021|archive-url=https://web.archive.org/web/20210731160224/https://www.who.int/news/item/08-05-2015-who-issues-best-practices-for-naming-new-human-infectious-diseases|url-status=live}}</ref>  Many authors now eschew calling this the Spanish flu,<ref name=fiction/> instead using variations of '1918–19/20 flu/influenza pandemic'.<ref>{{Cite web|url=https://www.who.int/influenza/pandemic-influenza-an-evolving-challenge/en/ |title=Pandemic influenza: an evolving challenge |date=22 May 2018 |website=World Health Organization |url-status=dead |archive-url= https://web.archive.org/web/20200320220124/https://www.who.int/influenza/pandemic-influenza-an-evolving-challenge/en/ |archive-date=20 March 2020 |access-date=20 March 2020}}</ref><ref>{{Cite web |url= https://www.britannica.com/event/influenza-pandemic-of-1918-1919 |title=Influenza pandemic of 1918–19 |date=4 March 2020 |website=[[Encyclopaedia Britannica]] |url-status=live |archive-url= https://web.archive.org/web/20200320220920/https://www.britannica.com/event/influenza-pandemic-of-1918-1919 |archive-date=20 March 2020 |access-date=20 March 2020}}</ref><ref>{{Cite news |vauthors=Chodosh S |url=https://www.popsci.com/story/health/coronavirus-1918-flu-pandemic/ |title=What the 1918 flu pandemic can teach us about COVID-19, in four charts |date=18 March 2020 |work=PopSci |access-date=20 March 2020 |archive-date=24 December 2020 | archive-url=https://web.archive.org/web/20201224025632/https://www.popsci.com/story/health/coronavirus-1918-flu-pandemic/ |url-status=live }}</ref>

===Local names===
Some language [[endonyms]] did not name specific regions or groups of people. Examples specific to this pandemic include: {{langx|nd|'Malibuzwe'}} (let enquiries be made concerning it), {{langx|sw|'Ugonjo huo kichwa na kukohoa na kiuno'}} (the disease of head and coughing and spine),<ref name="Muller-1998">{{Cite conference |vauthors=Mueller JW |date=1998 |title=What's in a name. Spanish Influenza in sub-Saharan Africa and what local names say about the perception of this pandemic |url=https://www.academia.edu/23653135 |conference=Spanish 'Flu 1918–1998: Reflections on the Influenza Pandemic of 1918 after 80 Years |place=Cape Town, South Africa |access-date=13 August 2021 |archive-date=30 November 2021 |archive-url=https://web.archive.org/web/20211130153656/https://www.academia.edu/23653135 |url-status=live }}</ref> {{langx|yao|'chipindupindu'}} (disease from seeking to make a profit in wartime), {{langx|hz|'kaapitohanga'}} (disease which passes through like a bullet),<ref>{{Cite web|vauthors=Phillips H|date=8 October 2014|title=Influenza Pandemic (Africa)|publisher=International Encyclopedia of the First World War (WW1)|url=https://encyclopedia.1914-1918-online.net/article/influenza_pandemic_africa|access-date=13 August 2021|website=encyclopedia.1914-1918-online.net|archive-date=13 August 2021|archive-url=https://web.archive.org/web/20210813130222/https://encyclopedia.1914-1918-online.net/article/influenza_pandemic_africa|url-status=live}}</ref><!--When it arrived in [[Tehran]] in [[Qajar Iran]] high winds were blamed for the rapid spread, so it was called the--> and {{langx|fa-Latn|<!--ناخوشی-ای باد-->nakhushi-yi bad}} (disease of the wind).<ref>{{Cite book|author=Great Britain Ministry of Health|url=https://books.google.com/books?id=FjxQAQAAMAAJ&q=the+affliction+was+called+%E2%80%9Cthe+disease+of+the+wind%22|title=Report on the Pandemic of Influenza, 1918–19|date=1920|publisher=H.M. Stationery Office|quote=There was a high west wind at the time and this was thought to be the carrying agent so that the affliction was called 'the disease of the wind.'|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014316/https://books.google.com/books?id=FjxQAQAAMAAJ&q=the+affliction+was+called+%E2%80%9Cthe+disease+of+the+wind%22#v=snippet&q=the%20affliction%20was%20called%20%E2%80%9Cthe%20disease%20of%20the%20wind%22&f=false|url-status=live}}</ref><ref>{{Cite book|vauthors=Afkhami AA|url=https://books.google.com/books?id=SiiGDwAAQBAJ&q=In+Tehran,+the+disease+was+called+the+%E2%80%9Cillness+of+the+wind%E2%80%9D+(nakhushi-yi+bad)&pg=PA157|title=A Modern Contagion: Imperialism and Public Health in Iran's Age of Cholera|date=5 February 2019|publisher=JHU Press|isbn=978-1-4214-2722-5|language=en|quote=In Tehran, the disease was called the "illness of the wind" (nakhushi-yi bad) due to its initial occurrence during a strong westerly wind burst and its rapid spread.|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014337/https://books.google.com/books?id=SiiGDwAAQBAJ&q=In+Tehran,+the+disease+was+called+the+%E2%80%9Cillness+of+the+wind%E2%80%9D+(nakhushi-yi+bad)&pg=PA157#v=snippet&q=In%20Tehran%2C%20the%20disease%20was%20called%20the%20%E2%80%9Cillness%20of%20the%20wind%E2%80%9D%20(nakhushi-yi%20bad)&f=false|url-status=live}}</ref>

===Other names===
This outbreak was also commonly known as the 'great influenza epidemic',<ref>{{Cite book|url=https://books.google.com/books?id=5HA6AQAAMAAJ&q=%22great+influenza+epidemic%22&pg=PA609|title=Archives of Internal Medicine|date=1919|volume=24|location=[[Chicago]]|publisher=[[American Medical Association]]|quote=As this included the period of the great influenza epidemic when Type IV infections were usually prevalent, it will be seen that the proportion of fixed types among carriers and among cases is not far from the same.|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014337/https://books.google.com/books?id=5HA6AQAAMAAJ&q=%22great+influenza+epidemic%22&pg=PA609#v=snippet&q=%22great%20influenza%20epidemic%22&f=false|url-status=live}}</ref><ref>{{Cite book|author=United States Surgeon-General's Office|url=https://books.google.com/books?id=rg9AAAAAYAAJ&q=%22great+influenza+epidemic%22&pg=PA2154|title=Report of the Surgeon-General of the Army to the Secretary of War for the Fiscal Year Ending June 30, 1919|series=War Department Annual Reports|volume=I|date=1920|publisher=U.S. Government Printing Office|quote=On September 13, 1918, the first cases of the great influenza epidemic were admitted, and during the next 10 weeks over 4,100 patients were admitted.|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014914/https://books.google.com/books?id=rg9AAAAAYAAJ&q=%22great+influenza+epidemic%22&pg=PA2154#v=snippet&q=%22great%20influenza%20epidemic%22&f=false|url-status=live}}</ref> after the 'great war', a common name for [[World War I]] before [[World War II]].{{sfn|Barry|2004b}} French military doctors originally called it 'disease 11' ({{lang|fr|maladie onze}}).<ref name="Müller"/> German doctors downplayed the severity by calling it 'pseudo influenza' ({{langx|la|link=no|pseudo}}, false), while in Africa, doctors tried to get patients to take it more seriously by calling it 'influenza vera' ({{langx|la|link=no|vera}}, true).<ref>{{harvnb|Spinney|2018|p=64}}: "In ... Rhodesia (Zimbabwe) ... officials labelled the new affliction 'influenza (vera)', adding the Latin word vera, meaning 'true' ... German doctors ... called it 'pseudo-influenza'"</ref>

A [[children's song]] from the 1889–90 flu pandemic<!-- also based on this mistaken idea that wind was a [[disease vector]],--><ref>{{Cite news|vauthors=Cross A|title=A look at art and music created in times of pandemic|url=https://globalnews.ca/news/6735528/alan-cross-art-pandemic-coronavirus/|date=29 March 2020|access-date=9 August 2021|work=Global News (Canada)|quote=Another rhyme with deadly origins appeared during a worldwide influenza pandemic in 1889–1890. Certain the disease could be stopped by sealing up the home from the poisoned air outside, this safety tip emerged in schools: There was a little girl, and she had a little bird; And she called it by the pretty name of Enza; But one day it flew away, but it didn't go to stay; For when she raised the window, in-flu-Enza|archive-date=10 August 2021|archive-url=https://web.archive.org/web/20210810020632/https://globalnews.ca/news/6735528/alan-cross-art-pandemic-coronavirus/|url-status=live}}</ref> was shortened and adapted into a [[skipping-rope rhyme]] popular in 1918.<ref>{{Cite web|author=University Libraries|title=WWI Exhibit: Influenza Pandemic|url=https://content.lib.washington.edu/exhibits/WWI/influenza.html|access-date=9 August 2021|website=content.lib.washington.edu|publisher=[[University of Washington]]|archive-date=9 August 2021|archive-url=https://web.archive.org/web/20210809125534/https://content.lib.washington.edu/exhibits/WWI/influenza.html|url-status=live}}</ref><ref>{{Cite book|vauthors=Hakim J|url=https://books.google.com/books?id=TYq1SeWvS9oC&q=I+had+a+little+bird,+And+its+name+was+Enza.+I+opened+up+the+window,+And+in+flew+Enza.&pg=PA21|title=War, Peace, and All that Jazz|year=2002|publisher=Oxford University Press|isbn=978-0-19-515335-4|quote=In flew Enza—say it fast and it becomes 'influenza.' It was a catchy little rhyme, and boys and girls skipped rope to it.|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014936/https://books.google.com/books?id=TYq1SeWvS9oC&q=I+had+a+little+bird,+And+its+name+was+Enza.+I+opened+up+the+window,+And+in+flew+Enza.&pg=PA21#v=snippet&q=I%20had%20a%20little%20bird%2C%20And%20its%20name%20was%20Enza.%20I%20opened%20up%20the%20window%2C%20And%20in%20flew%20Enza.&f=false|url-status=live}}</ref> It is a [[metaphor]] for the [[Transmission (medicine)|transmissibility]] of 'Influenza', where that name was [[Clipping (morphology)|clipped]] to 'Enza':<ref>{{Cite book|vauthors=Honigsbaum M|url=https://books.google.com/books?id=74RJDQAAQBAJ&q=Enza|title=Living with Enza: The Forgotten Story of Britain and the Great Flu Pandemic of 1918|year=2016|publisher=Springer|isbn=978-0-230-23921-0|quote=A popular playground skipping rhyme caught the ease with which this 'new disease' was transmitted: I had a little bird; Its name was Enza; I opened the window; And in-flu-enza. As influenza spread from Glasgow to Aberdeen, and from Liverpool to London's Mile End, it was not long before playgrounds throughout the country echoed to the chant.|archive-date=1 October 2024|access-date=24 August 2021|archive-url=https://web.archive.org/web/20241001014915/https://books.google.com/books?id=74RJDQAAQBAJ&q=Enza#v=snippet&q=Enza&f=false|url-status=live}}</ref><ref>{{cite news|vauthors=March PC|author-link=Peyton C. March|title=General March's Narrative: Glimpses of Woodrow Wilson|work=[[The New York Times]]|date=4 September 1932|page=XX3, Special Features section|url=https://www.nytimes.com/1932/09/04/archives/general-marchs-narrative-glimpses-of-woodrow-wilson-the-wartime.html|archive-date=10 August 2021|access-date=10 August 2021|archive-url=https://web.archive.org/web/20210810020628/https://www.nytimes.com/1932/09/04/archives/general-marchs-narrative-glimpses-of-woodrow-wilson-the-wartime.html|url-status=live}}</ref><ref>{{Cite magazine|title=The 1918 Flu Pandemic Killed Hundreds of Thousands of Americans. The White House Never Said a Word About It|url=https://time.com/5877129/1918-pandemic-white-house/|access-date=10 August 2021|magazine=Time|quote=Crosby's America's Forgotten Pandemic: The Influenza of 1918, Wilson asked Army Chief of Staff General Peyton March in October 1918 if he had heard of the popular jump rope rhyme parodying the virus, and recited part of it.|archive-date=10 August 2021|archive-url=https://web.archive.org/web/20210810020630/https://time.com/5877129/1918-pandemic-white-house/|url-status=live}}</ref>

{{poem quote| I had a little bird,<br />its name was Enza.<br />I opened the window,<br />and in-flu-enza.}}

==History==
===Timeline===
====First wave of early 1918====
[[File:Spanish flu in 1918, Police officers in masks, Seattle Police Department detail, from- 165-WW-269B-25-police-l (cropped).jpg|thumb|right|upright=1|[[Seattle]] policemen wearing cloth face masks handed out by the American Red Cross during the Spanish flu pandemic, December 1918]]
[[File:Parties Despite Influenza.png|thumb|300px|An article naming wealthy socialites for violating city law banning public gatherings, ''[[Chicago Tribune]]'', October 19, 1918. Named violators include Joan Pinkerton Chalmers, daughter of [[Pinkerton (detective agency)|Pinkertons]] private police founder [[Allan Pinkerton]].<ref>{{cite web |url=https://digitaledition.chicagotribune.com/tribune/article_popover.aspx?guid=d9a265d7-8b18-447a-8bdb-40121fae5c10 |title=The History of Pandemics in Chicago |publisher=[[Chicago Tribune]] |accessdate=2025-03-17 |archive-date=25 March 2025 |archive-url=https://web.archive.org/web/20250325222735/https://digitaledition.chicagotribune.com/tribune/article_popover.aspx?guid=d9a265d7-8b18-447a-8bdb-40121fae5c10 |url-status=live }}</ref>]]
The pandemic is conventionally marked as having begun on 4 March 1918 with the recording of the case of Albert Gitchell, an army cook at [[Camp Funston]] in [[Kansas]], United States, despite there having been cases before him.{{sfn|Spinney|2018|p=36}} The disease had already been observed {{convert|200|mi|km}} away in [[Haskell County, Kansas|Haskell County]] as early as January 1918, prompting local doctor [[Loring Miner]] to warn the editors of the [[U.S. Public Health Service]]'s journal ''Public Health Reports''.{{sfn|Barry|2004b}} Within days of the 4 March case at Camp Funston, 522 men at the camp had reported sick.<ref>{{cite web|title=1918 Flu (Spanish flu epidemic)|url=http://www.avian-bird-flu.info/spanishfluepidemic1918.html|archive-url=https://web.archive.org/web/20080521071645/http://www.avian-bird-flu.info/spanishfluepidemic1918.html|archive-date=21 May 2008|website=Avian Bird Flu}}</ref> By 11 March 1918, the virus had reached [[Queens]], New York.<ref>{{Cite web|vauthors=Sheidlower N|date=17 March 2020|title=How NYC Survived the 1918 Spanish Flu Pandemic|url=https://untappedcities.com/2020/03/17/how-nyc-survived-the-1918-spanish-flu-pandemic/|access-date=8 October 2020|website=Untapped New York|archive-date=29 September 2020|archive-url=https://web.archive.org/web/20200929134901/https://untappedcities.com/2020/03/17/how-nyc-survived-the-1918-spanish-flu-pandemic/|url-status=live}}</ref> Failure to take preventive measures in March/April was later criticized.{{sfn|Billings|1997}}

As the U.S. had entered World War I, the disease quickly spread from Camp Funston, a major training ground for troops of the [[American Expeditionary Forces]], to other [[United States Army|U.S. Army]] camps and Europe, becoming an epidemic in the [[Midwestern United States|Midwest]], [[East Coast of the United States|East Coast]], and French ports by April 1918, and reaching the [[Western Front (World War I)|Western Front]] by mid-April.{{sfn|Spinney|2018|p=36}} It then quickly spread to the rest of France, Great Britain, Italy, and Spain and in May reached [[Wrocław]] and [[Odessa]].{{sfn|Spinney|2018|p=36}} After the signing of the [[Treaty of Brest-Litovsk]] (March 1918), [[Germany]] started releasing Russian prisoners of war, who brought the disease to their country.<ref>{{Cite journal|date=2011|title=The Memoirs of Herbert Hoover: Years of Adventure, 1874–1920. (New York: Macmillan Company. 1951. pp. xi, 496.) and Herbert Hoover and the Russian Prisoners of World War I: A Study in Diplomacy and Relief, 1918–1919. By Edward F. Willis. (Stanford: Stanford University Press. 1951. pp. viii, 67.)|journal=The American Historical Review|page=12|doi=10.1086/ahr/57.3.709|issn=1937-5239}}</ref> It reached North Africa, India, and Japan in May, and soon after had likely gone around the world as there had been recorded cases in [[Southeast Asia]] in April.{{sfn|Spinney|2018|p=37}} In June an outbreak was reported in [[Republic of China (1912–1949)|China]].<ref>{{Cite news |date=1 June 1918 |title=Queer Epidemic Sweeps North China; Banks and Silk Stores in Peking Closed – Another Loan Sought from Japan. |work=[[The New York Times]] |url=https://www.nytimes.com/1918/06/01/archives/queer-epidemic-sweeps-north-china-banks-and-silk-stores-in-peking.html |access-date=22 June 2020 |issn=0362-4331  |archive-date=24 June 2020 |archive-url=https://web.archive.org/web/20200624031144/https://www.nytimes.com/1918/06/01/archives/queer-epidemic-sweeps-north-china-banks-and-silk-stores-in-peking.html |url-status=live }}</ref> After reaching Australia in July, the wave started to recede.{{sfn|Spinney|2018|p=37}}

The first wave lasted from the first quarter of 1918 and was relatively mild.{{sfn|Patterson|Pyle|1991}} Mortality rates were not appreciably above normal;{{sfn|Taubenberger|Morens|2006}} in the United States ~75,000 flu-related deaths were reported in the first six months of 1918, compared to ~63,000 deaths during the same time period in 1915.<ref name="CDCMortality1918">{{cite web |url=https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1918.pdf |title=Mortality Statistics 1918: Nineteenth Annual Report |publisher=[[United States Census Bureau]] |page=28 |date=1920 |access-date=29 May 2020 |archive-date=11 July 2020 |archive-url=https://web.archive.org/web/20200711052046/https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1918.pdf |url-status=live }}</ref> In Madrid, Spain, fewer than 1,000 people died from influenza between May and June 1918.<ref name="NIHInfluenza2010">{{cite journal | vauthors = Erkoreka A | title = The Spanish influenza pandemic in occidental Europe (1918–1920) and victim age | journal = Influenza and Other Respiratory Viruses | volume = 4 | issue = 2 | pages = 81–89 | date = March 2010 | pmid = 20167048 | pmc = 5779284 | doi = 10.1111/j.1750-2659.2009.00125.x }}</ref> There were no reported quarantines. However, the first wave caused a significant disruption in the military operations of [[World War I]], with three-quarters of French troops, half the British forces, and over 900,000 German soldiers sick.{{sfn|Spinney|2018|p=38}}

====Deadly second wave of late 1918====
[[File:USCampHospital45InfluenzaWard.jpg|thumb|left|upright=1.0|[[American Expeditionary Force]] flu patients at U.S. Army Camp Hospital no. 45 in [[Aix-les-Bains]], France, 1918]]
[[File:EsquellaFutbolTragic.jpg|alt=Spanish satirical cartoon published in November 1918 depicting a "tragic game of football" between Mars, Greek god of war, and the Spanish Flu. There is a short poem as a caption which roughly translates to English as "Between flu and war, look at how they've left her, our poor Earth"|left|thumb|[[Mars, God Of War|Mars, god of war]], plays a "tragic game of football" with a skeleton personification of the Spanish flu, November 1918]]
The second wave began in the second half of August 1918, probably spreading to [[Boston]], Massachusetts and [[Freetown]], Sierra Leone, by ships from [[Brest, France|Brest]], where it had likely arrived with American troops or French recruits for naval training.{{sfn|Spinney|2018|p=38}} From the [[Boston Navy Yard]] and [[Fort Devens|Camp Devens]], about {{convert|30|mi|km}} west of Boston, other U.S. military sites were soon afflicted, as were troops being transported to Europe.<ref>{{cite journal | vauthors = Byerly CR | title = The U.S. military and the influenza pandemic of 1918–1919 | journal = Public Health Reports | volume = 125 Suppl 3 | issue = Suppl 3 | pages = 82–91 | date = April 2010 | pmid = 20568570 | pmc = 2862337 | doi = 10.1177/00333549101250S311 }}</ref> Helped by troop movements, it spread over the next two months to all of North America, and then to Central and [[South America]], also reaching Brazil and the Caribbean on ships.{{sfn|Spinney|2018|p=39}} In July 1918, the [[Ottoman Empire]] saw its first cases, in soldiers.<ref name="www.sozcu.com.tr">{{Cite web |title=Atatürk işgalcilerden önce İspanyol Gribini yenmişti |url=https://www.sozcu.com.tr/2020/yazarlar/sinan-meydan/ataturk-isgalcilerden-once-ispanyol-gribini-yenmisti-5767483/ |access-date=2 November 2020 |website=sozcu.com.tr |date=23 April 2020 |language=tr |archive-date=8 November 2020 |archive-url=https://web.archive.org/web/20201108004306/https://www.sozcu.com.tr/2020/yazarlar/sinan-meydan/ataturk-isgalcilerden-once-ispanyol-gribini-yenmisti-5767483/ |url-status=live }}</ref> From Freetown, the pandemic spread through West Africa along the coast, rivers, and railways, and from railheads to more remote communities, while South Africa received it in September on ships bringing back members of the [[South African Native Labour Corps]] from France.{{sfn|Spinney|2018|p=39}} From there it spread around southern Africa and beyond the [[Zambezi]], reaching Ethiopia in November.{{sfn|Spinney|2018|p=40}} On 15 September, New York City saw its first fatality from influenza.<ref>{{cite book | vauthors = Barry JM  |title=The Great Influenza |publisher=Penguin Books |year=2005 |isbn=0-670-89473-7 |place=United States |page=270 |quote=On September 15, New York City's first influenza death occurred.}}</ref> The [[Philadelphia Liberty Loans Parade]], held in [[Philadelphia]], Pennsylvania, on 28 September 1918 to promote [[Liberty bond|government bonds]] for World War I, resulted in an outbreak causing 12,000 deaths.<ref name="philadelphia">{{cite news |vauthors=Flynn M |url=https://www.washingtonpost.com/nation/2020/03/12/pandemic-parade-flu-coronavirus/ |title=What happens if parades aren't canceled during pandemics? Philadelphia found out in 1918, with disastrous results. |date=12 March 2020 |newspaper=The Washington Post |access-date=9 July 2020 |archive-date=4 July 2020 |archive-url=https://web.archive.org/web/20200704064124/https://www.washingtonpost.com/nation/2020/03/12/pandemic-parade-flu-coronavirus/ |url-status=live }}</ref>

From Europe, the second wave swept through Russia in a southwest–northeast diagonal front, as well as being brought to [[Arkhangelsk]] by the [[North Russia intervention]], and then spread throughout [[Asia]] following the [[Russian Civil War]] and the [[Trans-Siberian Railway|Trans-Siberian railway]], reaching Iran (where it spread through [[Mashhad]]), and then India in September and China and Japan in October.{{sfn|Spinney|2018|p=41}} The celebrations of the [[Armistice of 11 November 1918]] also caused outbreaks in [[Lima]] and [[Nairobi]], but by December the wave was mostly over.{{sfn|Spinney|2018|p=42}}

The second wave of the 1918 pandemic was much more deadly than the first. The first wave had resembled typical flu epidemics; those most at risk were the sick and elderly, while younger, healthier people recovered easily. October 1918 was the month with the highest fatality rate of the whole pandemic.<ref>{{Cite episode |title=Influenza 1918 |episode-link=List of American Experience episodes#Season 10 (1997–98) |url=https://www.pbs.org/wgbh/americanexperience/films/influenza/ |series=American Experience |series-link=American Experience |vauthors=Kenner R |network=[[Public Broadcasting System|PBS]] |station=[[WGBH-TV|WGBH]] |date=18 January 2010 |season=10 |number=5 |transcript=Transcript |transcript-url=https://www.pbs.org/wgbh/americanexperience/films/influenza/#transcript |access-date=27 May 2020 |archive-date=27 May 2020 |archive-url=https://web.archive.org/web/20200527145233/https://www.pbs.org/wgbh/americanexperience/films/influenza/ |url-status=live }}</ref> In the United States, ~292,000 deaths were reported between September–December 1918, compared to ~26,000 during the same time period in 1915.<ref name="CDCMortality1918"/> The [[Netherlands]] reported over 40,000 deaths from influenza and acute respiratory disease. [[Bombay]] reported ~15,000 deaths in a population of 1.1 million.<ref name="EpidemicInfluenza">{{cite web |url=https://quod.lib.umich.edu/f/flu/8580flu.0016.858/47/--epidemic-influenza-a-survey?page=root;rgn=full+text;size=200;view=image |title=Epidemic Influenza |access-date=4 July 2020 |page=93 |archive-date=4 July 2020 |archive-url=https://web.archive.org/web/20200704055957/https://quod.lib.umich.edu/f/flu/8580flu.0016.858/47/--epidemic-influenza-a-survey?page=root;rgn=full+text;size=200;view=image |url-status=live }}</ref> The [[1918 flu pandemic in India]] was especially deadly, as Historian [[David Arnold (historian)|David Arnold]] estimates at least 12 million dead, about 5% of the population.<ref>{{Cite journal|doi=10.1017/S0080440119000082|title=Death and the Modern Empire: The 1918–19 Influenza Epidemic in India|year=2019|last1=Arnold|first1=David|journal=Transactions of the Royal Historical Society|volume=29|pages=181–200|s2cid=211656275 }}</ref>

====Third wave of 1919====
<!--"Spanish flu in Australia" redirects to this section--->[[File:“London, Registered Weekly Deaths from Influenza, Pneumonia and Bronchitis During 1918 and 1919” table on page 4 - Medical officer of health report on 1918 flu epidemic Wellcome L0046565 (cropped).jpg|thumb|304x304px|London weekly deaths from influenza during 1918 and 1919]]
Pandemic activity persisted into 1919 in many places, possibly attributable to climate, specifically in the [[Northern Hemisphere]], where it was winter and thus the usual time for influenza activity.<ref name="Chandra-2020">{{Cite journal | vauthors = Chandra S, Christensen J, Likhtman S |date=6 November 2020 |title=Connectivity and seasonality: the 1918 influenza and COVID-19 pandemics in global perspective |journal=Journal of Global History |volume=15 |issue=3 |pages=408–420 |doi=10.1017/S1740022820000261 |s2cid=228988279 |doi-access=free }}</ref><ref name="Bootsma-2007">{{cite journal | vauthors = Bootsma MC, Ferguson NM | title = The effect of public health measures on the 1918 influenza pandemic in U.S. cities | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 104 | issue = 18 | pages = 7588–7593 | date = May 2007 | pmid = 17416677 | pmc = 1849868 | doi = 10.1073/pnas.0611071104 | doi-access = free | bibcode = 2007PNAS..104.7588B }}</ref> The pandemic nonetheless continued into 1919 largely independent of region and climate.<ref name="Chandra-2020"/>

Cases began to rise again in some parts of the U.S. as early as late November 1918,<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for NOVEMBER 29, 1918 | journal = Public Health Reports | volume = 33 | issue = 48 | pages = 2093–2152 | date = November 1918 | pmid = 19314645 | pmc = 1999834 }}</ref> with the Public Health Service issuing its first report of a "recrudescence of the disease" in "widely scattered localities" in early December.<ref name="Public Health Reports-1918">{{cite journal | vauthors =  | title = Public Health Weekly Reports for DECEMBER 6, 1918 | journal = Public Health Reports | volume = 33 | issue = 49 | pages = 2153–2209 | date = December 1918 | pmid = 19314646 | pmc = 1999845 }}</ref> This resurgent activity varied across the country, however, possibly on account of differing restrictions.<ref name="Bootsma-2007"/> [[Michigan]], for example, experienced a swift resurgence of influenza that reached its peak in December, possibly as a result of the lifting of the ban on public gatherings.<ref>{{cite journal | vauthors = Chandra S, Christensen J, Chandra M, Paneth N | title = Pandemic Reemergence and Four Waves of Excess Mortality Coinciding With the 1918 Influenza Pandemic in Michigan: Insights for COVID-19 | journal = American Journal of Public Health | volume = 111 | issue = 3 | pages = 430–437 | date = March 2021 | pmid = 33566641 | pmc = 7893337 | doi = 10.2105/AJPH.2020.305969 }}</ref> Pandemic interventions, such as bans on public gatherings and the closing of schools, were reimposed in many places in an attempt to suppress the spread.<ref name="Public Health Reports-1918"/>

There was "a very sudden and very marked rise in general death rate" in most cities in January 1919; nearly all experienced "some degree of recrudescence" of the flu in January and February.<ref name="Jordan1927">{{Cite book |vauthors=Jordan EO |url=https://quod.lib.umich.edu/f/flu/8580flu.0016.858/--epidemic-influenza-a-survey?view=toc |title=Epidemic Influenza: A Survey |publisher=American Medical Association |year=1927 |location=Chicago |archive-date=17 March 2023 |access-date=17 March 2023 |archive-url=https://web.archive.org/web/20230317045405/https://quod.lib.umich.edu/f/flu/8580flu.0016.858/--epidemic-influenza-a-survey?view=toc |url-status=live }}</ref>{{rp|153–154}} Significant outbreaks occurred in cities including [[Los Angeles]],<ref name="LATimes1919">{{cite news |date=9 February 1919 |title=Here are Exact Facts About the Influenza and Its Toll in City, State, Nation, world |work=[[Los Angeles Times]] |url=https://quod.lib.umich.edu/f/flu/9980flu.0013.899/1/--here-are-exact-facts-about-the-influenza-and-its-toll?view=image |url-status=live |access-date=10 May 2020 |archive-url=https://web.archive.org/web/20200724115323/https://quod.lib.umich.edu/f/flu/9980flu.0013.899/1/--here-are-exact-facts-about-the-influenza-and-its-toll?view=image |archive-date=24 July 2020}}</ref> New York City,<ref name="NIH-NYC">{{cite journal | vauthors = Yang W, Petkova E, Shaman J | title = The 1918 influenza pandemic in New York City: age-specific timing, mortality, and transmission dynamics | journal = Influenza and Other Respiratory Viruses | volume = 8 | issue = 2 | pages = 177–188 | date = March 2014 | pmid = 24299150 | pmc = 4082668 | doi = 10.1111/irv.12217 | publisher = [[National Institutes of Health]] }}</ref> [[Memphis, Tennessee|Memphis]], [[Nashville]], [[San Francisco]], and [[St. Louis]].<ref name="Vaughan1921">{{cite journal | vauthors = Vaughan WT |date=July 1921 |title=Influenza: An Epidemiologic Study |url=https://books.google.com/books?id=Lhc6AQAAMAAJ&pg=PA1 |url-status=live |journal=[[American Journal of Epidemiology|American Journal of Hygiene]] |archive-url=https://web.archive.org/web/20200724111325/https://books.google.com/books?id=Lhc6AQAAMAAJ&pg=PA1 |archive-date=24 July 2020}}</ref>  By 21 February, with some local variation, influenza activity was reported to have been declining since mid-January in all parts of the country.<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for February 21, 1919 | journal = Public Health Reports | volume = 34 | issue = 8 | pages = 313–376 | date = February 1919 | pmid = 19314657 | pmc = 1996943 }}</ref> Following this "first great epidemic period" that had commenced in October 1918, deaths from pneumonia and influenza were "somewhat below average" in large U.S. cities between May 1919 and January 1920.{{r|Jordan1927|p=158}} Nonetheless, nearly 160,000 deaths were attributed to these causes in the first six months of 1919.<ref name="CDCMortality1919">{{cite web |date=1921 |title=Mortality Statistics 1919: Twentieth Annual Report |url=https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1919.pdf |url-status=live |archive-url=https://web.archive.org/web/20200712032041/https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1919.pdf |archive-date=12 July 2020 |access-date=11 May 2020 |publisher=[[United States Census Bureau]] |page=30}}</ref>

It was not until later in the winter and into the spring that a clearer resurgence appeared in Europe. A significant third wave had developed in [[England and Wales]] by mid-February, peaking in early March, though it did not fully subside until May.<ref>{{cite journal | vauthors = Pearce DC, Pallaghy PK, McCaw JM, McVernon J, Mathews JD | title = Understanding mortality in the 1918–1919 influenza pandemic in England and Wales | journal = Influenza and Other Respiratory Viruses | volume = 5 | issue = 2 | pages = 89–98 | date = March 2011 | pmid = 21306572 | pmc = 4954464 | doi = 10.1111/j.1750-2659.2010.00186.x }}</ref> France also experienced a significant wave that peaked in February, alongside the Netherlands. [[Norway]], [[Finland]], and [[Switzerland]] saw recrudescences of pandemic activity in March, and Sweden in April.<ref name="IORV2009">{{cite journal | vauthors = Ansart S, Pelat C, Boelle PY, Carrat F, Flahault A, Valleron AJ | title = Mortality burden of the 1918–1919 influenza pandemic in Europe | journal = Influenza and Other Respiratory Viruses | volume = 3 | issue = 3 | pages = 99–106 | date = May 2009 | pmid = 19453486 | pmc = 4634693 | doi = 10.1111/j.1750-2659.2009.00080.x }}</ref>

Much of Spain was affected by "a substantial recrudescent wave" of influenza between January and April 1919.<ref>{{cite journal | vauthors = Chowell G, Erkoreka A, Viboud C, Echeverri-Dávila B | title = Spatial-temporal excess mortality patterns of the 1918–1919 influenza pandemic in Spain | journal = BMC Infectious Diseases | volume = 14 | issue = 371 | pages = 371 | date = July 2014 | pmid = 24996457 | pmc = 4094406 | doi = 10.1186/1471-2334-14-371 | doi-access = free }}</ref> Portugal experienced a resurgence in pandemic activity that lasted from March to September 1919, with the greatest impact being felt on the west coast and in the north of the country; all districts were affected between April and May specifically.<ref>{{cite journal | vauthors = Nunes B, Silva S, Rodrigues A, Roquette R, Batista I, Rebelo-de-Andrade H | title = The 1918–1919 Influenza Pandemic in Portugal: A Regional Analysis of Death Impact | journal = American Journal of Epidemiology | volume = 187 | issue = 12 | pages = 2541–2549 | date = December 2018 | pmid = 30099487 | pmc = 7314274 | doi = 10.1093/aje/kwy164 }}</ref>

Influenza entered Australia for the first time in January 1919 after a strict maritime quarantine had shielded the country through 1918.<ref name="Holbrook-2022">{{cite journal | vauthors = Holbrook C | title = Public Health in a Federation: Lessons from the Spanish Influenza in Australia | journal = Social History of Medicine | volume = 35 | issue = 3 | pages = 818–846 | date = August 2022 | pmid = 36046217 | pmc = 9383459 | doi = 10.1093/shm/hkac005 }}</ref> It assumed epidemic proportions first in [[Melbourne]], peaking in mid-February.<ref name="Shanks">{{Cite web |vauthors=Shanks GD |title=Australia's Experience of the 1918–19 Influenza Pandemic: Lessons Learned |url=https://www.otago.ac.nz/wellington/otago711857.pdf |website=University of Otago |access-date=17 March 2023 |archive-date=19 September 2020 |archive-url=https://web.archive.org/web/20200919223943/https://www.otago.ac.nz/wellington/otago711857.pdf |url-status=live }}</ref> The flu soon appeared in neighboring [[New South Wales]] and [[South Australia]].<ref name="Holbrook-2022" /> New South Wales experienced its first wave of infection between mid-March and late May,<ref name="Curson-2006">{{cite journal | vauthors = Curson P, McCracken K | title = An Australian perspective of the 1918–1919 influenza pandemic | journal = New South Wales Public Health Bulletin | volume = 17 | issue = 7–8 | pages = 103–107 | date = 2006 | pmid = 17136138 | doi = 10.1071/NB06025 | doi-access = free }}</ref> while a second, more severe wave occurred in [[Victoria, Australia|Victoria]] between April and June.<ref name="Shanks"/> Land quarantine measures hindered the spread of the disease. [[Queensland]] was not infected until late April; [[Western Australia]] avoided the disease until early June, and [[Tasmania]] remained free from it until mid-August.<ref name="Holbrook-2022"/> Out of the six states, Victoria and New South Wales experienced generally more extensive epidemics. Each experienced another significant wave of illness over the winter. The second epidemic in New South Wales was more severe than the first,<ref name="Curson-2006"/> while Victoria saw a third wave that was somewhat less extensive than its second, more akin to its first.<ref name="Shanks"/>

The disease also reached other parts of the world for the first time in 1919, such as [[Madagascar]], which saw its first cases in April; the outbreak had spread to practically all sections of the island by June.<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for AUGUST 22, 1919 | journal = Public Health Reports | volume = 34 | issue = 34 | pages = 1927–1968 | date = August 1919 | pmid = 19314683 | pmc = 1996930 }}</ref> In other parts, influenza recurred in the form of a true "third wave". [[British Hong Kong|Hong Kong]] experienced another outbreak in June,<ref>{{cite journal | vauthors = Ho PL, Chow KH | title = Mortality burden of the 1918–1920 influenza pandemic in Hong Kong | journal = Influenza and Other Respiratory Viruses | volume = 3 | issue = 6 | pages = 261–263 | date = November 2009 | pmid = 19903207 | pmc = 4941390 | doi = 10.1111/j.1750-2659.2009.00105.x }}</ref> as did South Africa during its fall and winter months in the [[Southern Hemisphere]].<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for MAY 30, 1919 | journal = Public Health Reports | volume = 34 | issue = 22 | pages = 1171–1241 | date = May 1919 | pmid = 19314671 | pmc = 1996920 }}</ref><ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for AUGUST 1, 1919 | journal = Public Health Reports | volume = 34 | issue = 31 | pages = 1673–1742 | date = August 1919 | pmid = 19314680 | pmc = 1996928 }}</ref><ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for AUGUST 29, 1919 | journal = Public Health Reports | volume = 34 | issue = 35 | pages = 1969–2012 | date = August 1919 | pmid = 19314684 | pmc = 1996931 }}</ref> [[Dominion of New Zealand|New Zealand]] experienced some cases in May.<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for AUGUST 15, 1919 | journal = Public Health Reports | volume = 34 | issue = 33 | pages = 1823–1926 | date = August 1919 | pmid = 19314682 | pmc = 1996932 }}</ref>

Parts of South America experienced a resurgence of pandemic activity throughout 1919. A third wave hit Brazil between January and June.<ref name="Chandra-2020"/> Between July 1919 and February 1920, [[Chile]], which had been affected for the first time in October 1918, experienced a severe second wave, with mortality peaking in August 1919.<ref name="Chowell-2014">{{cite journal | vauthors = Chowell G, Simonsen L, Flores J, Miller MA, Viboud C | title = Death patterns during the 1918 influenza pandemic in Chile | journal = Emerging Infectious Diseases | volume = 20 | issue = 11 | pages = 1803–1811 | date = November 2014 | pmid = 25341056 | pmc = 4214284 | doi = 10.3201/eid2011.130632 }}</ref> [[Montevideo]] similarly experienced a second outbreak between July and September.<ref>{{cite journal | vauthors = Cristina J, Pollero R, Pellegrino A | title = The 1918 influenza pandemic in Montevideo: The southernmost capital city in the Americas | journal = Influenza and Other Respiratory Viruses | volume = 13 | issue = 3 | pages = 219–225 | date = May 2019 | pmid = 30422393 | pmc = 6468140 | doi = 10.1111/irv.12619 }}</ref>

The third wave particularly affected Spain, [[Serbia]], [[Mexico]] and Great Britain, resulting in hundreds of thousands of deaths.<ref name="CollegePhysiciansPhiladelphia">{{cite web |url=https://www.historyofvaccines.org/content/blog/influenza-1919-2019 |title=Influenza in 1919 and 100 Years Later |vauthors=Najera RF |publisher=[[College of Physicians of Philadelphia]] |date=2 January 2019 |access-date=23 April 2020 |archive-date=24 July 2020 |archive-url=https://web.archive.org/web/20200724110351/https://www.historyofvaccines.org/content/blog/influenza-1919-2019 |url-status=live }}</ref>

====Fourth wave of 1920====
[[File:Illustrated Current News-1918-Thompson, Paul.png|thumb|Public health recommendations from the ''Illustrated Current News''|upright=1.2]]
In the Northern Hemisphere, fears of a "recurrence" of the flu grew as fall approached. Experts cited past flu epidemics, such as that of 1889–1890, to predict that such a recurrence a year later was not unlikely,<ref>{{cite journal | vauthors =  | title = Public Health Weekly Reports for AUGUST 15, 1919 | journal = Public Health Reports | volume = 34 | issue = 33 | pages = 1823–1926 | date = August 1919 | pmid = 19314682 | pmc = 1996932 | doi = 10.2307/4575271 | jstor = 4575271 }}</ref><ref>{{Cite news |date=15 August 1919 |title=WARNS OF INFLUENZA. |page=6 |work=The New York Times |url=https://www.nytimes.com/1919/08/15/archives/warns-of-influenza-health-commissioner-expects-visitation-this.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031216/https://www.nytimes.com/1919/08/15/archives/warns-of-influenza-health-commissioner-expects-visitation-this.html |url-status=live }}</ref> though not all agreed.<ref>{{Cite news |date=27 August 1919 |title=AT ISSUE WITH COPELAND. |page=9 |work=The New York Times |url=https://www.nytimes.com/1919/08/27/archives/at-issue-with-copeland-cincinnati-health-officer-expects-no.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031215/https://www.nytimes.com/1919/08/27/archives/at-issue-with-copeland-cincinnati-health-officer-expects-no.html |url-status=live }}</ref> In September 1919, [[Surgeon General of the United States|U.S. Surgeon General]] [[Rupert Blue]] said a return of the flu later in the year would "probably, but by no means certainly," occur.<ref>{{Cite news |date=14 September 1919 |title=INFLUENZA RETURN EXPECTED BY BLUE |pages=4 |work=The New York Times |url=https://www.nytimes.com/1919/09/14/archives/influenza-return-expected-by-blue-pandemic-in-mild-form-likely-this.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031220/https://www.nytimes.com/1919/09/14/archives/influenza-return-expected-by-blue-pandemic-in-mild-form-likely-this.html |url-status=live }}</ref> France had readied a public information campaign before the end of the summer,<ref>{{Cite news |date=19 August 1919 |title=PARIS FEARS RETURN OF "FLU" EPIDEMIC |pages=4 |work=The Sun |url=https://chroniclingamerica.loc.gov/lccn/sn83030431/1919-08-20/ed-1/seq-4/ |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413025708/https://chroniclingamerica.loc.gov/lccn/sn83030431/1919-08-20/ed-1/seq-4/ |url-status=live }}</ref> and Britain began preparations in the autumn with the manufacture of vaccine.<ref>{{Cite news |date=30 October 1919 |title=British Prepare for Influenza. |pages=17 |work=The New York Times |url=https://www.nytimes.com/1919/10/30/archives/british-prepare-for-influenza.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031213/https://www.nytimes.com/1919/10/30/archives/british-prepare-for-influenza.html |url-status=live }}</ref>

In Japan, the flu broke out again in December and spread rapidly throughout the country, a fact attributed at the time to cold weather.<ref>{{Cite news |date=28 December 1919 |title=GRIP IS EPIDEMIC IN JAPAN. |pages=6 |work=The New York Times |url=https://www.nytimes.com/1919/12/28/archives/grip-is-epidemic-in-japan-measures-to-check-it-taken-by-tokio.html |access-date=17 March 2023 |archive-date=17 March 2023 |archive-url=https://web.archive.org/web/20230317035353/https://www.nytimes.com/1919/12/28/archives/grip-is-epidemic-in-japan-measures-to-check-it-taken-by-tokio.html |url-status=live }}</ref><ref name="The Honolulu Advertiser-1920">{{Cite news |date=10 January 1920 |title=Influenza Gradually Spreading In Japan |pages=3 |work=The Honolulu Advertiser |url=https://www.newspapers.com/image/268433358/ |access-date=17 March 2023 |archive-date=17 March 2023 |archive-url=https://web.archive.org/web/20230317035351/https://www.newspapers.com/image/268433358/ |url-status=live }}</ref> Pandemic-related measures were renewed to check the outbreak, and health authorities recommended the use of masks.<ref name="The Honolulu Advertiser-1920"/> The epidemic intensified in the latter part of December before swiftly peaking in January.<ref name="The Sydney Morning Herald-1920">{{Cite news |date=28 January 1920 |title=INFLUENZA IN JAPAN. |pages=10 |work=The Sydney Morning Herald |url=https://www.newspapers.com/image/97220933/ |access-date=17 March 2023 |archive-date=21 March 2023 |archive-url=https://web.archive.org/web/20230321222346/https://www.newspapers.com/image/97220933/ |url-status=live }}</ref>

Between October 1919 and 23 January 1920, 780,000 cases were reported across the country, with at least 20,000 deaths recorded by that date. This apparently reflected "a condition of severity three times greater than for the corresponding period of" 1918–1919.<ref name="The Sydney Morning Herald-1920" /> Nonetheless, the disease was regarded as being milder than it had been the year before, albeit more infectious.<ref>{{Cite news |date=26 January 1920 |title=INFLUENZA. |pages=5 |work=The Age |url=https://www.newspapers.com/image/126640866/ |access-date=17 March 2023 |archive-date=21 March 2023 |archive-url=https://web.archive.org/web/20230321222335/https://www.newspapers.com/image/126640866/ |url-status=live }}</ref> Despite its rapid peak at the beginning of the year, the outbreak persisted throughout the winter, before subsiding in the spring.<ref name="World Health Organization-2013">{{cite journal | vauthors = Richard SA, Sugaya N, Simonsen L, Miller MA, Viboud C | title = A comparative study of the 1918–1920 influenza pandemic in Japan, USA and UK: mortality impact and implications for pandemic planning | journal = Epidemiology and Infection | volume = 137 | issue = 8 | pages = 1062–1072 | date = August 2009 | pmid = 19215637 | pmc = 2704924 | doi = 10.1017/S0950268809002088 }}</ref>

In the United States, there were "almost continuously isolated or solitary cases" of flu throughout the spring and summer of 1919.<ref name="EpidemologicStudy">{{cite web |date=July 1921 |title=Influenza: An Epidemologic Study |url=https://quod.lib.umich.edu/f/flu/0980flu.0016.890/108/--influenza-an-epidemiologic-study?page=root;size=100;view=image;q1=1920 |url-status=live |archive-url=https://web.archive.org/web/20201006063708/https://quod.lib.umich.edu/f/flu/0980flu.0016.890/108/--influenza-an-epidemiologic-study?page=root;size=100;view=image;q1=1920 |archive-date=6 October 2020 |access-date=13 August 2020 |publisher=The American Journal of Hygiene |page=91 |vauthors=Vaughan WT}}</ref> An increase in scattered cases became apparent as early as September,<ref>{{Cite news |date=28 September 1919 |title=300 "FLU" CASES REPORTED |pages=5 |work=The New York Times |url=https://www.nytimes.com/1919/09/28/archives/300-flu-cases-reported-31-in-this-stateall-said-to-be-of-mild-type.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031223/https://www.nytimes.com/1919/09/28/archives/300-flu-cases-reported-31-in-this-stateall-said-to-be-of-mild-type.html |url-status=live }}</ref> but Chicago experienced one of the first major outbreaks of the flu beginning in the middle of January.<ref>{{Cite news |date=15 January 1920 |title=Influenza Spreads in Chicago |pages=1 |work=The New York Times |url=https://www.nytimes.com/1920/01/15/archives/influenza-spreads-in-chicago-106-new-cases-and-one-death.html |access-date=12 April 2022 |archive-date=22 March 2023 |archive-url=https://web.archive.org/web/20230322035543/https://www.nytimes.com/1920/01/15/archives/influenza-spreads-in-chicago-106-new-cases-and-one-death.html |url-status=live }}</ref> The Public Health Service announced it would take steps to "localize the epidemic",<ref>{{Cite news |date=17 January 1920 |title=525 NEW CASES IN CHICAGO. |pages=11 |work=The New York Times |url=https://www.nytimes.com/1920/01/17/archives/525-new-cases-in-chicago-influenza-spreading-rapidly-there-health.html |access-date=12 April 2022}}</ref> but the disease was already causing a simultaneous outbreak in Kansas City and quickly spread outward from the center of the country.<ref name="EpidemologicStudy" /> A few days after its first announcement, PHS issued another assuring that the disease was under the control of state health authorities and that an outbreak of epidemic proportions was not expected.<ref>{{Cite news |date=21 January 1920 |title=Health Service Reports Influenza Under Control in All Parts of the Country |pages=A2 |work=The Evening Star |url=https://chroniclingamerica.loc.gov/lccn/sn83045462/1920-01-21/ed-1/seq-2/ |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413030008/https://chroniclingamerica.loc.gov/lccn/sn83045462/1920-01-21/ed-1/seq-2/ |url-status=live }}</ref>

It became apparent within days of the start of Chicago's explosive growth in cases that the flu was spreading in the city at an even faster rate than in winter 1919, though fewer were dying.<ref>{{Cite news |date=18 January 1920 |title=CHICAGO INFLUENZA EPIDEMIC SPREADS |pages=14 |work=The New York Times |url=https://www.nytimes.com/1920/01/18/archives/chicago-influenza-epidemic-spreads-two-thousand-new-cases-are.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031214/https://www.nytimes.com/1920/01/18/archives/chicago-influenza-epidemic-spreads-two-thousand-new-cases-are.html |url-status=live }}</ref> Within a week, new cases in the city had surpassed its peak during the 1919 wave.<ref>{{Cite news |date=21 January 1920 |title=INFLUENZA CASES INCREASE IN CHICAGO |pages=32 |work=The New York Times |url=https://www.nytimes.com/1920/01/21/archives/influenza-cases-increase-in-chicago-disease-now-regarded-as.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031217/https://www.nytimes.com/1920/01/21/archives/influenza-cases-increase-in-chicago-disease-now-regarded-as.html |url-status=live }}</ref> Around the same time, New York City began to see its own sudden increase in cases,<ref>{{Cite news |date=21 January 1920 |title=INFLUENZA SHOWS A LARGE INCREASE |pages=32 |work=The New York Times |url=https://www.nytimes.com/1920/01/21/archives/influenza-shows-a-large-increase-health-department-reports-140-new.html |access-date=12 April 2022 |archive-date=22 March 2023 |archive-url=https://web.archive.org/web/20230322035538/https://www.nytimes.com/1920/01/21/archives/influenza-shows-a-large-increase-health-department-reports-140-new.html |url-status=live }}</ref> and other cities around the country were soon to follow.<ref>{{Cite news |date=23 January 1920 |title=SPREADS IN OTHER CITIES. |pages=2 |work=The New York Times |url=https://www.nytimes.com/1920/01/23/archives/spreads-in-other-cities-more-influenza-cases-reported-in.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413025709/https://www.nytimes.com/1920/01/23/archives/spreads-in-other-cities-more-influenza-cases-reported-in.html |url-status=live }}</ref> Certain pandemic restrictions, such as the closing of schools and theaters and the staggering of business hours to avoid congestion, were reimposed in cities like Chicago,<ref>{{Cite news |date=22 January 1920 |title=TOPICS OF THE TIMES. |pages=16 |work=The New York Times |url=https://www.nytimes.com/1920/01/22/archives/topics-of-the-times-the-return-of-the-influenza-menace.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031220/https://www.nytimes.com/1920/01/22/archives/topics-of-the-times-the-return-of-the-influenza-menace.html |url-status=live }}</ref> Memphis,<ref name="The New York Times-1920">{{Cite news |date=25 January 1920 |title=INFLUENZA CASES GROW THROUGHOUT COUNTRY |pages=2 |work=The New York Times |url=https://www.nytimes.com/1920/01/25/archives/influenza-cases-grow-throughout-country-chicago-sees-evidence-of.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031215/https://www.nytimes.com/1920/01/25/archives/influenza-cases-grow-throughout-country-chicago-sees-evidence-of.html |url-status=live }}</ref> and New York City.<ref name="The New York Times-1920-2">{{Cite news |date=27 January 1920 |title=COPELAND EXPECTS RISE IN INFLUENZA |pages=1 |work=The New York Times |url=https://www.nytimes.com/1920/01/27/archives/copeland-expects-rise-in-influenza-monday-reports-show-only-1712.html |access-date=12 April 2022 |archive-date=22 March 2023 |archive-url=https://web.archive.org/web/20230322035549/https://www.nytimes.com/1920/01/27/archives/copeland-expects-rise-in-influenza-monday-reports-show-only-1712.html |url-status=live }}</ref> As they had during the epidemic in fall 1918, schools in New York City remained open,<ref name="The New York Times-1920-2" /> while those in Memphis were shuttered as part of restrictions on public gatherings.<ref name="The New York Times-1920"/>

[[File:1918 flu in Oakland.jpg|thumb|[[American Red Cross]] nurses tend to flu patients in temporary wards set up inside the [[Oakland, California|Oakland]] Municipal Auditorium]]
The fourth wave in the United States subsided as swiftly as it had appeared, reaching a peak in early February.<ref>{{Cite news |date=8 February 1920 |title=Influenza Checked in 25 States. |pages=15 |work=The New York Times |url=https://www.nytimes.com/1920/02/08/archives/influenza-checked-in-25-states.html |access-date=12 April 2022 |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413031213/https://www.nytimes.com/1920/02/08/archives/influenza-checked-in-25-states.html |url-status=live }}</ref> "An epidemic of considerable proportions marked the early months of 1920", the U.S. Mortality Statistics would later note; according to data at this time, the epidemic resulted in one third as many deaths as the 1918–1919 experience.<ref>{{Cite report |work=US Bureau of the Census |title=Mortality statistics, 1920. Twenty-First Annual Report. |date=1922 |url=https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1920.pdf |via=CDC |archive-date=16 March 2023 |access-date=13 April 2022 |archive-url=https://web.archive.org/web/20230316205252/https://www.cdc.gov/nchs/data/vsushistorical/mortstatsh_1920.pdf |url-status=live }}</ref> New York City alone reported 6,374 deaths between December 1919 and April 1920, almost twice the number of the first wave in spring 1918.<ref name="NIH-NYC"/> Detroit, Milwaukee, Kansas City, Minneapolis, and St. Louis were hit particularly hard, with death rates higher than all of 1918.<ref name="Vaughan1921" /> [[Territory of Hawaii|Hawaii]] experienced its peak of the pandemic in early 1920, recording 1,489 deaths from flu-related causes, compared with 615 in 1918 and 796 in 1919.<ref>{{Cite journal |vauthors=Schmitt RC, Nordyke EC |date=1999 |title=Influenza Deaths in Hawai'i, 1918—1920 |url=https://evols.library.manoa.hawaii.edu/handle/10524/538 |journal=Hawaiian Journal of History |volume=33 |pages=101–117 |via=eVols |archive-date=5 July 2022 |access-date=13 April 2022 |archive-url=https://web.archive.org/web/20220705000357/https://evols.library.manoa.hawaii.edu/handle/10524/538 |url-status=live }}</ref>

Poland experienced a devastating outbreak during the winter months, with its capital [[Warsaw]] reaching a peak of 158 deaths in a single week, compared to the peak of 92 in December 1918; however, the 1920 epidemic passed in a matter of weeks, while the 1918–1919 wave had developed over the entire second half of 1918.<ref>{{cite journal | vauthors = Grabowski ML, Kosińska B, Knap JP, Brydak LB | title = The Lethal Spanish Influenza Pandemic in Poland | journal = Medical Science Monitor | volume = 23 | pages = 4880–4884 | date = October 2017 | pmid = 29021518 | pmc = 5649514 | doi = 10.12659/MSM.906280 }}</ref> By contrast, the outbreak in western Europe was considered "benign", with the age distribution of deaths beginning to take on that of [[Flu season|seasonal flu]].<ref name="NIHInfluenza2010"/> Spain, Denmark, Finland, Germany and Switzerland recorded a late peak between January–April 1920.<ref name="IORV2009"/>

Mexico experienced a fourth wave between February and March. In South America, [[Peru]] experienced "asynchronous recrudescent waves" throughout the year. A severe third wave hit [[Lima]], the capital city, between January and March, resulting in an all-cause excess mortality rate approximately four times greater than that of the 1918–1919 wave. [[Ica, Peru|Ica]] similarly experienced another severe pandemic wave in 1920, between July and October.<ref>{{cite journal | vauthors = Chowell G, Viboud C, Simonsen L, Miller MA, Hurtado J, Soto G, Vargas R, Guzman MA, Ulloa M, Munayco CV | title = The 1918–1920 influenza pandemic in Peru | journal = Vaccine | volume = 29 Suppl 2 | issue = Suppl 2 | pages = B21–B26 | date = July 2011 | pmid = 21757099 | pmc = 3144394 | doi = 10.1016/j.vaccine.2011.02.048 }}</ref> A fourth wave also occurred in Brazil, in February.<ref name="Chandra-2020"/>

[[Korea under Japanese rule|Korea]] and [[Taiwan under Japanese rule|Taiwan]] experienced pronounced outbreaks in late 1919 and early 1920.<ref>{{Cite journal |vauthors=Kim T |date=2017 |title=The 1918 Influenza Pandemic and Japanese Government-General of Korea's Preventive Measures against Epidemics |url=http://journal.kci.go.kr/snu-ioh/archive/articleView?artiId=ART002202446 |journal=Journal of Humanities, Seoul National University |language=Korean |volume=74 |issue=1 |pages=203–207 |via=Korea Journal Central |archive-date=17 March 2023 |access-date=17 March 2023 |archive-url=https://web.archive.org/web/20230317035414/http://journal.kci.go.kr/snu-ioh/archive/articleView?artiId=ART002202446 |url-status=live }}</ref><ref>{{cite journal | vauthors = Hsieh YH | title = Excess deaths and immunoprotection during 1918–1920 influenza pandemic, Taiwan | journal = Emerging Infectious Diseases | volume = 15 | issue = 10 | pages = 1617–1619 | date = October 2009 | pmid = 19861055 | pmc = 2866376 | doi = 10.3201/eid1510.080811 }}</ref>

====Post-pandemic====
By mid-1920, the pandemic was largely considered to be "over" by the public as well as governments.<ref>{{Cite journal |vauthors=Nichols CM, Ewing ET, Gaston KH, Marinari M, Lessoff A, Huyssen D |date=April 2022 |title=What Came Next?: Reflections on the Aftermath(s) of the 1918–19 Flu Pandemic in the Age of COVID |url=https://www.cambridge.org/core/journals/journal-of-the-gilded-age-and-progressive-era/article/abs/what-came-next-reflections-on-the-aftermaths-of-the-191819-flu-pandemic-in-the-age-of-covid/C34A023067C72795D6CFAB2A365AF66A |journal=The Journal of the Gilded Age and Progressive Era |volume=21 |issue=2 |pages=126 |via=Cambridge Core |archive-date=27 February 2023 |access-date=17 March 2023 |archive-url=https://web.archive.org/web/20230227183514/https://www.cambridge.org/core/journals/journal-of-the-gilded-age-and-progressive-era/article/abs/what-came-next-reflections-on-the-aftermaths-of-the-191819-flu-pandemic-in-the-age-of-covid/C34A023067C72795D6CFAB2A365AF66A |url-status=live }}</ref> Though parts of Chile experienced a third, milder wave between November 1920 and March 1921,<ref name="Chowell-2014" /> the flu seemed to be mostly absent through the winter of 1920–1921.{{r|Jordan1927|p=167}} In the United States, for example, deaths from pneumonia and influenza were "very much lower than for many years".{{r|Jordan1927|p=167}}

Seasonal influenza began to be reported again from many places in 1921.{{r|Jordan1927|p=168}} Influenza continued to be felt in Chile, where a post-pandemic fourth wave affected 7 of its 24 provinces between June and December 1921.<ref name="Chowell-2014"/> The winter of 1921–1922 was the first major reappearance of seasonal influenza in the Northern Hemisphere, in many parts its most significant occurrence since the main pandemic in late 1918. Northwestern Europe was particularly affected. All-cause mortality in the [[Netherlands]] approximately doubled in January 1922 alone.{{r|Jordan1927|p=168}} In [[Helsinki]], a major epidemic (the fifth since 1918) prevailed between November and December 1921.<ref>{{Cite book | vauthors = Linnanmäki E |title=Espanjantauti Suomessa — Influenssapandemia 1918–1920 |publisher=Suomalaisen Kirjallisuuden Seura |year=2005 |isbn=9789517467162 |location=Helsinki |pages=69 |language=fi}}</ref> The flu was also widespread in the United States, its prevalence in California reportedly greater in early March 1922 than at any point since the pandemic ended in 1920.{{r|Jordan1927|p=172}}

In the years after 1920, the disease came to represent the "seasonal flu". The virus, H1N1, remained endemic, occasionally causing more severe or [[Flu season#Notable occurrences|otherwise notable outbreaks]].<ref name="Taubenberger-2010">{{cite journal | vauthors = Taubenberger JK, Morens DM | title = Influenza: the once and future pandemic | journal = Public Health Reports | volume = 125 Suppl 3 | issue = Suppl 3 | pages = 16–26 | date = April 2010 | pmid = 20568566 | pmc = 2862331 | doi = 10.1177/00333549101250S305 }}</ref> The period since its initial appearance in 1918 has been termed a "pandemic era", in which all flu pandemics have been caused by its own descendants.<ref>{{cite journal | vauthors = Morens DM, Taubenberger JK, Fauci AS | title = The persistent legacy of the 1918 influenza virus | journal = The New England Journal of Medicine | volume = 361 | issue = 3 | pages = 225–229 | date = July 2009 | pmid = 19564629 | pmc = 2749954 | doi = 10.1056/NEJMp0904819 }}</ref> Following the [[1957–1958 influenza pandemic|first of these post-1918 pandemics]], in 1957, the virus was totally displaced by the novel [[Influenza A virus subtype H2N2|H2N2]], the [[Reassortment|reassortant]] product of the human H1N1 and an [[avian influenza]] virus, which thereafter became the active influenza A virus in humans.<ref name="Taubenberger-2010"/>

In 1977, an influenza virus bearing a very close resemblance to the seasonal H1N1, which had not been seen since the 1950s, appeared in Russia and subsequently initiated a "technical" [[1977 Russian flu|pandemic]] that principally affected those 26 and under.<ref name="Taubenberger-2009">{{cite journal | vauthors = Taubenberger JK, Morens DM | title = Pandemic influenza – including a risk assessment of H5N1 | journal = Revue Scientifique et Technique | volume = 28 | issue = 1 | pages = 187–202 | date = April 2009 | pmid = 19618626 | pmc = 2720801 | doi = 10.20506/rst.28.1.1879 }}</ref><ref name="Rozo-2015">{{cite journal | vauthors = Rozo M, Gronvall GK | title = The Reemergent 1977 H1N1 Strain and the Gain-of-Function Debate | journal = mBio | volume = 6 | issue = 4 | date = August 2015 | pmid = 26286690 | pmc = 4542197 | doi = 10.1128/mBio.01013-15 }}</ref> While some natural explanations, such as the virus remaining in some frozen state for 20 years,<ref name="Rozo-2015"/> have been proposed to explain this unprecedented<ref>{{cite journal | vauthors = Kung HC, Jen KF, Yuan WC, Tien SF, Chu CM | title = Influenza in China in 1977: recurrence of influenzavirus A subtype H1N1 | journal = Bulletin of the World Health Organization | volume = 56 | issue = 6 | pages = 913–918 | date = 1978 | pmid = 310732 | pmc = 2395678 | hdl = 10665/261795 }}</ref> phenomenon, the nature of influenza itself has been cited in favor of human involvement of some kind, such as an accidental leak from a lab where the old virus had been preserved for research purposes.<ref name="Rozo-2015"/> Following this miniature pandemic, the reemerged H1N1 became endemic again but did not displace the other active influenza A virus, [[Influenza A virus subtype H3N2|H3N2]] (which itself had displaced H2N2 through a [[Hong Kong flu|pandemic in 1968]]).<ref name="Taubenberger-2009"/><ref name="Taubenberger-2010"/> For the first time, two influenza A viruses were observed in cocirculation.<ref name="Saunders-Hastings_2016"/> This state has persisted even after 2009, when a [[Pandemic H1N1/09 virus|novel H1N1 virus]] emerged, sparked a [[2009 swine flu pandemic|pandemic]], and thereafter took the place of the seasonal H1N1 to circulate alongside H3N2.<ref name="Saunders-Hastings_2016"/>

===Potential origins===
Despite its name, historical and [[epidemiology|epidemiological]] data cannot identify the geographic origin of the Spanish flu.{{sfn|Taubenberger|Morens|2006}} However, several theories have been proposed.

====United States====
The first confirmed cases originated in the United States. Historian [[Alfred W. Crosby]] stated in 2003 that the flu originated in [[Kansas]],{{sfn|Crosby|2003}} and author [[John M. Barry]] described a January 1918 outbreak in [[Haskell County, Kansas]], as the origin in his 2004 article.{{sfn|Barry|2004b}}

A 2018 study of tissue slides and medical reports led by professor Michael Worobey found evidence against the disease originating from Kansas, as those cases were milder and had fewer deaths compared to the infections in New York City in the same period. The study did find evidence through [[phylogenetic analyses]] that the virus likely had a North American origin, though it was not conclusive. In addition, the [[Hemagglutinin (influenza)|haemagglutinin glycoproteins]] of the virus suggest that it originated long before 1918, and other studies suggest that the reassortment of the H1N1 virus likely occurred in or around 1915.<ref name="WorobeyStudy">{{cite journal | vauthors = Worobey M, Cox J, Gill D | title = The origins of the great pandemic | journal = Evolution, Medicine, and Public Health | volume = 2019 | issue = 1 | pages = 18–25 | date = 2019 | pmid = 30805187 | pmc = 6381288 | doi = 10.1093/emph/eoz001 | s2cid = 67863937 }}</ref>

====Europe====
[[File:Edvard Munch - Self-Portrait with the Spanish Flu - NG.M.01867 - National Museum of Art, Architecture and Design.jpg|thumb|[[Edvard Munch]] (1863–1944), ''Self-Portrait with the Spanish Flu'' (1919)]]
The major UK troop staging and hospital camp in [[Étaples]] in France has been theorized by virologist [[John Oxford]] as being at the center of the Spanish flu.<ref name="npr"/> His study found that in late 1916 the Étaples camp was hit by a new disease with high mortality that caused symptoms similar to the flu.<ref name="Oxford 2001a">{{cite journal | vauthors = Oxford JS | title = The so-called Great Spanish Influenza Pandemic of 1918 may have originated in France in 1916 | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 356 | issue = 1416 | pages = 1857–1859 | date = December 2001 | pmid = 11779384 | pmc = 1088561 | doi = 10.1098/rstb.2001.1012 | publisher = [[Royal Society]] | author-link = John Oxford }}</ref><ref name="npr">{{cite web| vauthors = Valentine V |date=20 February 2006 |title=Origins of the 1918 Pandemic: The Case for France |url=https://www.npr.org/templates/story/story.php?storyId=5222069 |publisher=[[National Public Radio]] |access-date=13 April 2020 |archive-url= https://web.archive.org/web/20090430101332/https://www.npr.org/templates/story/story.php?storyId=5222069 |archive-date=30 April 2009 |url-status=live}}</ref> According to Oxford, a similar outbreak occurred in March 1917 at army barracks in [[Aldershot]],<ref name="Etaples"/> and military pathologists later recognized these early outbreaks as the same disease as the Spanish flu.<ref name="oxford:0"/><ref name="npr"/>

The overcrowded camp and hospital at Étaples was an ideal environment for the spread of a respiratory virus. The hospital treated thousands of victims of [[Chemical weapons in World War I|poison gas]] attacks, and other casualties of war. It also was home to a [[piggery]] and [[poultry]] was regularly brought in to feed the camp. Oxford and his team postulated that a precursor virus, harbored in birds, [[Mutation|mutated]] and then migrated to pigs kept near the front.<ref name="Etaples">{{cite news | vauthors = Connor S |url=http://www.independent.co.uk/life-style/health-and-wellbeing/health-news/flu-epidemic-traced-to-great-war-transit-camp-728112.html |title=Flu epidemic traced to Great War transit camp |newspaper=The Guardian |place=UK |date=8 January 2000 |access-date=9 May 2009 |archive-url=https://web.archive.org/web/20090808003837/http://www.independent.co.uk/life-style/health-and-wellbeing/health-news/flu-epidemic-traced-to-great-war-transit-camp-728112.html |url-status=dead |archive-date=8 August 2009}}</ref><ref name="oxford:0">{{cite journal | vauthors = Oxford JS, Lambkin R, Sefton A, Daniels R, Elliot A, Brown R, Gill D | title = A hypothesis: the conjunction of soldiers, gas, pigs, ducks, geese and horses in northern France during the Great War provided the conditions for the emergence of the "Spanish" influenza pandemic of 1918–1919 | journal = Vaccine | volume = 23 | issue = 7 | pages = 940–945 | date = January 2005 | pmid = 15603896 | doi = 10.1016/j.vaccine.2004.06.035 | url = https://www.faculty.umb.edu/peter_taylor/epi/oxford05.pdf | access-date = 12 March 2020 | url-status = dead | archive-url = https://web.archive.org/web/20200312192929/https://www.faculty.umb.edu/peter_taylor/epi/oxford05.pdf | archive-date = 12 March 2020 }}</ref>
A report published in 2016 in the ''Journal of the [[Chinese Medical Association]]'' found evidence that the 1918 virus had been circulating in the European armies for months and possibly years before the 1918 pandemic.<ref name="JotCMA79">{{cite journal | vauthors = Shanks GD | title = No evidence of 1918 influenza pandemic origin in Chinese laborers/soldiers in France | journal = Journal of the Chinese Medical Association | volume = 79 | issue = 1 | pages = 46–48 | date = January 2016 | pmid = 26542935 | doi = 10.1016/j.jcma.2015.08.009 | doi-access = free }}</ref> Political scientist [[Andrew Price-Smith]] published data from the [[Austrian archives]] suggesting the influenza began in Austria in early 1917.{{sfn|Price-Smith|2008}}

A 2009 study in ''[[Influenza and Other Respiratory Viruses]]'' found that Spanish flu mortality simultaneously peaked within the two-month period of October and November 1918 in all fourteen European countries analyzed, which is inconsistent with the pattern that researchers would expect if the virus had originated somewhere in Europe and then spread outwards.<ref name="IORV2009"/>

====China====
In 1993, Claude Hannoun, the leading expert on the Spanish flu at the [[Pasteur Institute]], asserted the precursor virus was likely to have come from China and then mutated in the United States near [[Boston]] and from there spread to [[Brest, France|Brest]], France, Europe's battlefields, and the rest of the world, with [[Allies of World War I|Allied]] forces as the main disseminators.<ref name="Hannoun">{{cite conference| vauthors = Hannoun C |year=1993|title=Documents de la Conférence de l'Institut Pasteur|conference=La Grippe Espagnole de 1918|series=Ed Techniques Encyclopédie Médico-Chirurgicale (EMC), Maladies infectieuses|volume=8-069-A-10|article=La Grippe}}</ref> Hannoun considered several alternative hypotheses of origin, such as Spain, Kansas, and Brest, as being possible, but not likely.<ref name="Hannoun"/>

In 2014, historian Mark Humphries of the [[Memorial University of Newfoundland]] argued that the mobilization of 96,000 [[Chinese Labour Corps|Chinese laborers]] to work behind the British and French lines might have been the source of the pandemic. Humphries found archival evidence that a respiratory illness that struck northern China (where the laborers came from) in November 1917 was identified a year later by Chinese health officials as identical to the Spanish flu.{{sfn|Humphries|2014}}<ref name="Vergano">{{cite news| vauthors = Vergano D |date=24 January 2014 |title= 1918 Flu Pandemic That Killed 50 Million Originated in China, Historians Say|magazine=[[National Geographic (magazine)|National Geographic]] |url= http://news.nationalgeographic.com/news/2014/01/140123-spanish-flu-1918-china-origins-pandemic-science-health/|url-status=dead |access-date=4 November 2016|archive-url=https://web.archive.org/web/20140126185316/http://news.nationalgeographic.com/news/2014/01/140123-spanish-flu-1918-china-origins-pandemic-science-health/|archive-date=26 January 2014}}</ref> No tissue samples have survived for modern comparison.{{sfn|Spinney|2018|p=143}} Nevertheless, there were some reports of respiratory illness on the path the laborers took to get to Europe, which also passed through North America.{{sfn|Spinney|2018|p=143}}

China was one of the few regions of the world seemingly less affected by the Spanish flu pandemic, where several studies have documented a comparatively mild flu season in 1918.<ref name="Killingray-2003">{{Cite book |vauthors=Killingray D, Phillips H |url=https://books.google.com/books?id=k79_8QX8n44C&q=The+Spanish+Influenza+Pandemic+of+1918-1919:+New+Perspectives |title=The Spanish Influenza Pandemic of 1918–1919: New Perspectives |publisher=Routledge |year=2003 |isbn=978-1-134-56640-2 |access-date=9 November 2020 |archive-date=9 May 2021 |archive-url=https://web.archive.org/web/20210509133323/https://books.google.com/books?id=k79_8QX8n44C&q=The+Spanish+Influenza+Pandemic+of+1918-1919:+New+Perspectives |url-status=live }}</ref><ref name="Langford_2005">{{cite journal | vauthors = Langford C |year=2005 |title=Did the 1918–19 Influenza Pandemic Originate in China?|journal=Population and Development Review |volume=31 |issue=3 |pages=473–505 |doi=10.1111/j.1728-4457.2005.00080.x |jstor=3401475 }}</ref><ref name="Cheng_2007">{{cite journal | vauthors = Cheng KF, Leung PC | title = What happened in China during the 1918 influenza pandemic? | journal = International Journal of Infectious Diseases | volume = 11 | issue = 4 | pages = 360–364 | date = July 2007 | pmid = 17379558 | doi = 10.1016/j.ijid.2006.07.009 | doi-access = free }}</ref> (This is disputed due to lack of data during the [[Warlord Era|Warlord Period]].) This has led to speculation that the Spanish flu pandemic originated in China,<ref name="Cheng_2007"/><ref>{{cite magazine | vauthors = Vergano D |url= https://www.nationalgeographic.com/news/2014/1/140123-spanish-flu-1918-china-origins-pandemic-science-health/ |title=1918 Flu Pandemic That Killed 50 Million Originated in China, Historians Say |magazine=National Geographic |access-date=5 March 2020 |archive-url= https://web.archive.org/web/20200303220347/https://www.nationalgeographic.com/news/2014/1/140123-spanish-flu-1918-china-origins-pandemic-science-health/ |archive-date=3 March 2020 |url-status=dead}}</ref> as the lower mortality rates may be explained by the Chinese population's previously [[acquired immunity]] to the flu virus.<ref name="Saunders-Hastings_2016">{{cite journal | vauthors = Saunders-Hastings PR, Krewski D | title = Reviewing the History of Pandemic Influenza: Understanding Patterns of Emergence and Transmission | journal = Pathogens | volume = 5 | issue = 4 | page = 66 | date = December 2016 | pmid = 27929449 | pmc = 5198166 | doi = 10.3390/pathogens5040066 | doi-access = free }}</ref><ref name="Cheng_2007"/> In the [[Guangdong|Guangdong Province]] it was reported that early outbreaks of influenza in 1918 disproportionately impacted young men. The June outbreak infected children and adolescents between 11 and 20 years of age, while the October outbreak was most common in those aged 11 to 15.<ref name="Cheng_2007"/>

A report published in 2016 in the ''Journal of the Chinese Medical Association'' found no evidence that the 1918 virus was imported to Europe via Chinese and Southeast Asian soldiers and workers and instead found evidence of its circulation in Europe before the pandemic.<ref name="JotCMA79"/> The 2016 study found that the low flu mortality rate (an estimated one in a thousand) recorded among the Chinese and Southeast Asian workers in Europe suggests that the Asian units were not different from other Allied military units in France at the end of 1918 and, thus not a likely source of a new lethal virus.<ref name="JotCMA79"/> Further evidence against the disease being spread by Chinese workers was that workers entered Europe through other routes that did not result in a detectable spread, making them unlikely to have been the original hosts.<ref name="WorobeyStudy"/>

==Epidemiology and pathology==
===Transmission and mutation===
[[File:U.S. Army Field Hospital No. 29, Hollerich, Luxembourg Interior view- Influenza ward.jpg|thumb|U.S. Army flu patients at Field Hospital No. 29 near Hollerich, Luxembourg 1918. As U.S. troops deployed en masse for the [[United States in World War I|war effort in Europe]], they carried the Spanish flu with them.]]
The [[basic reproduction number]] of the virus was between 2 and 3.<ref>{{cite journal | vauthors = Mills CE, Robins JM, Lipsitch M | title = Transmissibility of 1918 pandemic influenza | journal = Nature | volume = 432 | issue = 7019 | pages = 904–906 | date = December 2004 | pmid = 15602562 | pmc = 7095078 | doi = 10.1038/nature03063 | bibcode = 2004Natur.432..904M }}</ref> The close quarters and massive troop movements of [[World War I]] hastened the pandemic, and probably both increased transmission and augmented mutation. The war may also have reduced people's resistance to the virus. Some speculate the soldiers' immune systems were weakened by malnourishment and the stresses of combat and chemical attacks, increasing their susceptibility.{{sfn|Qureshi|2016|p=42}}{{sfn|Ewald|1994}} Modern transportation systems and increased travel was a significant factor in the worldwide occurrence.<ref>{{Cite web|title=The Spanish Flu pandemic of 1918|url=https://www.thehistorypress.co.uk/articles/the-spanish-flu-pandemic-of-1918/|url-status=live|access-date=20 February 2021|website=The History Press|archive-date=13 January 2021|archive-url=https://web.archive.org/web/20210113105135/https://www.thehistorypress.co.uk/articles/the-spanish-flu-pandemic-of-1918/}}</ref> Another was lies and denial by governments, leaving the population ill-prepared to handle the outbreaks.<ref name="Illing">{{cite web | vauthors = Illing S |title=The most important lesson of the 1918 influenza pandemic: Tell the damn truth |url=https://www.vox.com/coronavirus-covid19/2020/3/20/21184887/coronavirus-covid-19-spanish-flu-pandemic-john-barry |website=Vox |archive-url=https://web.archive.org/web/20200325172129/https://www.vox.com/coronavirus-covid19/2020/3/20/21184887/coronavirus-covid-19-spanish-flu-pandemic-john-barry |archive-date=25 March 2020|date=20 March 2020 |quote=John M. Barry : The government lied. They lied about everything. We were at war and they lied because they didn't want to upend the war effort. You had public health leaders telling people this was just the ordinary flu by another name. They simply didn't tell the people the truth about what was happening. |url-status=live}}</ref>

The severity of the second wave has been attributed to the First World War.{{sfn|Gladwell|1997|p=55}} In civilian life, [[natural selection]] favors a mild strain. Those who get very ill stay home, and those mildly ill continue with their lives, preferentially spreading the mild strain. In the trenches, natural selection was reversed. Soldiers with a mild strain stayed where they were, while the severely ill were sent on crowded trains to crowded field hospitals, spreading the deadlier virus. The second wave began, and the flu quickly spread around the world again. (During modern pandemics, health officials look for deadlier strains of a virus when it reaches places with social upheaval.{{sfn|Gladwell|1997|p=63}}) The fact that most of those who recovered from first-wave infections had become [[Immunity (medical)|immune]] showed that it must have been the same strain of flu. This was most dramatically illustrated in [[Copenhagen]], which escaped with a combined mortality rate of 0.29% (0.02% in the first wave and 0.27% in the second wave) because of exposure to the less-lethal first wave.<ref>{{cite web|author=Fogarty International Center|title=Summer Flu Outbreak of 1918 May Have Provided Partial Protection Against Lethal Fall Pandemic|url=http://www.fic.nih.gov/News/GlobalHealthMatters/Pages/Flu-1918.aspx|url-status=live|archive-url=https://web.archive.org/web/20110727122221/http://www.fic.nih.gov/News/GlobalHealthMatters/Pages/Flu-1918.aspx|archive-date=27 July 2011|access-date=19 May 2012|publisher=Fic.nih.gov}}</ref>

After the lethal second wave, new cases dropped abruptly. In Philadelphia, for example, 4,597 people died in the week ending 16 October, but by 11 November, influenza had almost disappeared from the city. One explanation for the rapid decline in lethality is that doctors became more effective in the prevention and treatment of pneumonia that developed after the victims had contracted the virus. However, John Barry stated in his 2004 book ''[[The Great Influenza: The Epic Story of the Deadliest Plague In History]]'' that researchers have found no evidence to support this position.{{sfn|Barry|2004b}} Another theory holds that the 1918 virus mutated extremely rapidly to a less lethal strain. Such [[evolution of influenza]] is a common occurrence: there is a tendency for pathogenic viruses to become less lethal with time, as the hosts of more dangerous strains tend to die out.{{sfn|Barry|2004b}} Fatal cases did continue into 1919, however. One notable example was that of [[ice hockey]] player [[Joe Hall (ice hockey)|Joe Hall]], who died of the flu in April after an outbreak that resulted in the cancellation of the [[1919 Stanley Cup Finals]].<ref>{{Cite web | vauthors = Joyce G |date=March 2020 |title=The 1919 Stanley Cup Final and modern-history's deadliest pandemic |url=https://www.sportsnet.ca/hockey/nhl/1919-stanley-cup-spanish-flu-pandemic/ |archive-url=https://web.archive.org/web/20200331024901/https://www.sportsnet.ca/hockey/nhl/1919-stanley-cup-spanish-flu-pandemic/ |archive-date=31 March 2020 |access-date=23 March 2023 |website=Sportsnet}}</ref>

===Signs and symptoms===
[[File:3548786222 7a3d3208d3 bInfluenzaGrippe.jpg|thumb|US Army symptomology of the flu]]
The majority of the infected experienced only the typical flu symptoms of sore throat, headache, and fever, especially during the first wave.{{sfn|Spinney|2018|pp=45–47}} However, during the second wave, the disease was much more serious, often complicated by [[bacterial pneumonia]], which was often the cause of death.{{sfn|Spinney|2018|pp=45–47}} This more serious type would cause ''heliotrope cyanosis'' to develop, whereby the skin would first develop two mahogany spots over the cheekbones which would then over a few hours color the entire face blue, followed by black coloration first in the extremities and then the limbs and the torso.{{sfn|Spinney|2018|pp=45–47}} Death would follow within hours or days due to the lungs being filled with fluids.{{sfn|Spinney|2018|pp=45–47}} Other signs and symptoms reported included spontaneous mouth and nosebleeds, miscarriages for pregnant women, a peculiar smell, teeth and hair falling out, [[delirium]], dizziness, insomnia, loss of hearing or smell, and impaired vision.{{sfn|Spinney|2018|pp=45–47}} One observer wrote, "One of the most striking of the complications was [[hemorrhage]] from [[mucous membrane]]s, especially from the nose, stomach, and intestine. Bleeding from the ears and [[petechia|petechial hemorrhages]] in the skin also occurred".{{sfn|Knobler|2005}}

The majority of deaths were from [[bacterial pneumonia]],<ref name="MorrisCleary2017">{{cite journal | vauthors = Morris DE, Cleary DW, Clarke SC | title = Secondary Bacterial Infections Associated with Influenza Pandemics | journal = Frontiers in Microbiology | volume = 8 | pages = 1041 | year = 2017 | pmid = 28690590 | pmc = 5481322 | doi = 10.3389/fmicb.2017.01041 | doi-access = free }}</ref><ref>{{cite web |title=Bacterial Pneumonia Caused Most Deaths in 1918 Influenza Pandemic |url=https://www.nih.gov/news-events/news-releases/bacterial-pneumonia-caused-most-deaths-1918-influenza-pandemic |website=National Institutes of Health |date=23 September 2015 |access-date=17 April 2016 |archive-url=https://web.archive.org/web/20160422191021/https://www.nih.gov/news-events/news-releases/bacterial-pneumonia-caused-most-deaths-1918-influenza-pandemic |archive-date=22 April 2016 |url-status=live}}</ref>{{sfn|Taubenberger|Reid|Janczewski|Fanning|2001|pp=1829–39}} a common [[secondary infection]] associated with influenza. This pneumonia was itself caused by common upper respiratory-tract bacteria, which were able to get into the lungs via the damaged [[Bronchus|bronchial tubes]].<ref>{{cite journal | vauthors = Morens DM, Taubenberger JK, Fauci AS | title = Predominant role of bacterial pneumonia as a cause of death in pandemic influenza: implications for pandemic influenza preparedness | journal = The Journal of Infectious Diseases | volume = 198 | issue = 7 | pages = 962–970 | date = October 2008 | pmid = 18710327 | pmc = 2599911 | doi = 10.1086/591708 }}</ref> The virus also killed people directly by causing massive hemorrhages and [[edema]] in the lungs.{{sfn|Taubenberger|Reid|Janczewski|Fanning|2001|pp=1829–39}} Modern analysis has shown the virus to be particularly deadly because in animal trials it triggers an overreaction of the body's immune system ([[cytokine storm]]).{{sfn|Barry|2004b}} The strong immune reactions of young adults were postulated to have ravaged the body, whereas the weaker immune reactions of children and middle-aged adults resulted in fewer deaths.{{sfn|Barry|2004}}

===Misdiagnosis===
Because the virus that caused the disease was too small to be seen under a microscope at the time, there were problems with correctly diagnosing it.{{sfn|Spinney|2018|p=61}} The bacterium ''[[Haemophilus influenzae]]'' was instead mistakenly thought to be the cause, as it was big enough to be seen and was present in many, though not all, patients.{{sfn|Spinney|2018|p=61}} For this reason, a vaccine that was used against that bacillus did not make infection rarer but did decrease the death rate.<ref>{{Cite news |title=Washington State Board of Health pessimistic about influenza pandemic in a report to the governor on January 1, 1919. |url=https://www.historylink.org/File/20313 |access-date=21 July 2020 |website=historylink.org |archive-date=21 July 2020 |archive-url=https://web.archive.org/web/20200721231319/https://www.historylink.org/File/20313 |url-status=live }}</ref>

During the deadly second wave there were also fears that it was in fact [[Plague (disease)|plague]], [[dengue fever]], or [[cholera]].{{sfn|Spinney|2018|p=62}} Another misdiagnosis was [[typhus]], which was common in circumstances of social upheaval, and was therefore also affecting Russia in the aftermath of the [[October Revolution]].{{sfn|Spinney|2018|p=62}} In [[Chile]], the view of the country's elite was that the nation was in severe decline, and therefore doctors assumed that the disease was typhus caused by poor hygiene, causing a mismanaged response which did not ban mass gatherings.{{sfn|Spinney|2018|p=62}}

===Role of climate conditions===
[[File:CoughsAndSneezesSpreadDiseases.jpg|thumb|Poster with the slogan "[[Coughs and sneezes spread diseases]]" ]]
Studies have shown that the immune system of Spanish flu victims could have been weakened by unseasonably cold and wet weather for extended periods during the pandemic. This affected especially troops exposed to incessant rains and lower-than-average temperatures during World War I, and especially during the second wave of the pandemic. Climate data and mortality records analyzed at [[Harvard University]] and the Climate Change Institute at the [[University of Maine]] identified a severe climate anomaly that impacted Europe from 1914 to 1919, with several environmental indicators directly influencing the severity and spread of the pandemic.<ref name="The Impact of a Six‐Year Climate An"/> Specifically, a significant increase in precipitation affected all of Europe during the second wave of the pandemic, from September to December 1918. Mortality figures follow closely the concurrent increase in precipitation and decrease in temperatures. Several explanations have been proposed for this, including that lower temperatures and increased precipitation provided ideal conditions for virus replication and transmission, while also negatively affecting peoples' immune systems, a factor proven to increase likelihood of infection by both viruses and pneumococcal co-morbid infections documented to have affected a large percentage of pandemic victims (one fifth of them, with a 36% mortality rate).<ref>{{cite journal | vauthors = Foxman EF, Storer JA, Fitzgerald ME, Wasik BR, Hou L, Zhao H, Turner PE, Pyle AM, Iwasaki A | title = Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 112 | issue = 3 | pages = 827–832 | date = January 2015 | pmid = 25561542 | pmc = 4311828 | doi = 10.1073/pnas.1411030112 | doi-access = free | bibcode = 2015PNAS..112..827F }}</ref><ref>{{cite journal | vauthors = Lowen AC, Steel J | title = Roles of humidity and temperature in shaping influenza seasonality | journal = Journal of Virology | volume = 88 | issue = 14 | pages = 7692–7695 | date = July 2014 | pmid = 24789791 | pmc = 4097773 | doi = 10.1128/JVI.03544-13 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Brown JD, Goekjian G, Poulson R, Valeika S, Stallknecht DE | title = Avian influenza virus in water: infectivity is dependent on pH, salinity and temperature | journal = Veterinary Microbiology | volume = 136 | issue = 1–2 | pages = 20–26 | date = April 2009 | pmid = 19081209 | doi = 10.1016/j.vetmic.2008.10.027 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Foxman EF, Storer JA, Vanaja K, Levchenko A, Iwasaki A | title = Two interferon-independent double-stranded RNA-induced host defense strategies suppress the common cold virus at warm temperature | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 113 | issue = 30 | pages = 8496–8501 | date = July 2016 | pmid = 27402752 | pmc = 4968739 | doi = 10.1073/pnas.1601942113 | doi-access = free | bibcode = 2016PNAS..113.8496F }}</ref><ref>{{cite journal | vauthors = Klugman KP, Chien YW, Madhi SA | title = Pneumococcal pneumonia and influenza: a deadly combination | journal = Vaccine | volume = 27 Suppl 3 | issue = s3 | pages = C9–C14 | date = August 2009 | pmid = 19683658 | doi = 10.1016/j.vaccine.2009.06.007 | doi-access = free }}</ref> The climate anomaly likely influenced the migration of H1N1 avian vectors which contaminate bodies of water with their droppings, reaching 60% infection rates in autumn.<ref>{{cite journal | vauthors = Bengtsson D, Safi K, Avril A, Fiedler W, Wikelski M, Gunnarsson G, Elmberg J, Tolf C, Olsen B, Waldenström J | title = Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host? | journal = Royal Society Open Science | volume = 3 | issue = 2 | pages = 150633 | date = February 2016 | pmid = 26998334 | pmc = 4785985 | doi = 10.1098/rsos.150633 | bibcode = 2016RSOS....350633B | doi-access = free }}</ref><ref>{{cite journal | vauthors = Tolf C, Bengtsson D, Rodrigues D, Latorre-Margalef N, Wille M, Figueiredo ME, Jankowska-Hjortaas M, Germundsson A, Duby PY, Lebarbenchon C, Gauthier-Clerc M, Olsen B, Waldenström J | title = Birds and viruses at a crossroad – surveillance of influenza A virus in Portuguese waterfowl | journal = PLOS ONE | volume = 7 | issue = 11 | pages = e49002 | year = 2012 | pmid = 23145046 | pmc = 3492218 | doi = 10.1371/journal.pone.0049002 | bibcode = 2012PLoSO...749002T | doi-access = free }}</ref><ref>{{cite journal | vauthors = Tucker MA, Böhning-Gaese K, Fagan WF, Fryxell JM, Van Moorter B, Alberts SC, Ali AH, Allen AM, Attias N, Avgar T, Bartlam-Brooks H, Bayarbaatar B, Belant JL, Bertassoni A, Beyer D, Bidner L, van Beest FM, Blake S, Blaum N, Bracis C, Brown D, de Bruyn PJ, Cagnacci F, Calabrese JM, Camilo-Alves C, Chamaillé-Jammes S, Chiaradia A, Davidson SC, Dennis T, DeStefano S, Diefenbach D, Douglas-Hamilton I, Fennessy J, Fichtel C, Fiedler W, Fischer C, Fischhoff I, Fleming CH, Ford AT, Fritz SA, Gehr B, Goheen JR, Gurarie E, Hebblewhite M, Heurich M, Hewison AJ, Hof C, Hurme E, Isbell LA, Janssen R, Jeltsch F, Kaczensky P, Kane A, Kappeler PM, Kauffman M, Kays R, Kimuyu D, Koch F, Kranstauber B, LaPoint S, Leimgruber P, Linnell JD, López-López P, Markham AC, Mattisson J, Medici EP, Mellone U, Merrill E, de Miranda Mourão G, Morato RG, Morellet N, Morrison TA, Díaz-Muñoz SL, Mysterud A, Nandintsetseg D, Nathan R, Niamir A, Odden J, O'Hara RB, Oliveira-Santos LG, Olson KA, Patterson BD, Cunha de Paula R, Pedrotti L, Reineking B, Rimmler M, Rogers TL, Rolandsen CM, Rosenberry CS, Rubenstein DI, Safi K, Saïd S, Sapir N, Sawyer H, Schmidt NM, Selva N, Sergiel A, Shiilegdamba E, Silva JP, Singh N, Solberg EJ, Spiegel O, Strand O, Sundaresan S, Ullmann W, Voigt U, Wall J, Wattles D, Wikelski M, Wilmers CC, Wilson JW, Wittemyer G, Zięba F, Zwijacz-Kozica T, Mueller T | title = Moving in the Anthropocene: Global reductions in terrestrial mammalian movements | journal = Science | volume = 359 | issue = 6374 | pages = 466–469 | date = January 2018 | pmid = 29371471 | doi = 10.1126/science.aam9712 | hdl-access = free | doi-access = free | bibcode = 2018Sci...359..466T | hdl = 10174/25640 }}</ref> The climate anomaly has been associated with an anthropogenic increase in atmospheric dust, due to the incessant bombardment; increased nucleation due to dust particles ([[cloud condensation nuclei]]) contributed to increased precipitation.<ref>{{cite news |vauthors=Blakemore E |title=Catastrophic effect of 1918 flu may have been aided by peculiar influx of cold air into Europe during WWI |url=https://www.washingtonpost.com/science/spanish-flu-1918-climate/2020/10/02/9b730432-0339-11eb-a2db-417cddf4816a_story.html |newspaper=The Washington Post |access-date=29 November 2020 |date=3 October 2020 |archive-date=11 December 2020 |archive-url=https://web.archive.org/web/20201211234431/https://www.washingtonpost.com/science/spanish-flu-1918-climate/2020/10/02/9b730432-0339-11eb-a2db-417cddf4816a_story.html |url-status=live }}</ref><ref>{{cite news |vauthors=Kent L |title=How environmental conditions like cold and wet weather can affect pandemics, and what that means for COVID-19 |url=https://www.cnn.com/2020/09/28/health/climate-affects-pandemics-new-study-trnd-scn/index.html |publisher=[[CNN]] |access-date=29 November 2020 |date=28 September 2020 |archive-date=2 December 2020 |archive-url=https://web.archive.org/web/20201202121649/https://www.cnn.com/2020/09/28/health/climate-affects-pandemics-new-study-trnd-scn/index.html |url-status=live }}</ref><ref>{{cite web |vauthors=Powell A |title=Six-year deluge linked to Spanish flu, World War I deaths |url=https://news.harvard.edu/gazette/story/2020/10/study-offers-clues-to-how-climate-affected-1918-pandemic/ |website=Harvard Gazette |access-date=29 November 2020 |date=5 October 2020 |archive-date=27 November 2020 |archive-url=https://web.archive.org/web/20201127204714/https://news.harvard.edu/gazette/story/2020/10/study-offers-clues-to-how-climate-affected-1918-pandemic|url-status=live }}</ref>

==Responses==
===Public health management===
{{multiple image
| align             = right
| direction         = horizontal
| total_width       = 350
| image1            = Coromandel_Hospital_Board.jpg
| width1            =
| caption1          = Coromandel Hospital Board ([[Dominion of New Zealand|New Zealand]]) advice to influenza sufferers (1918)
| image2            = 19180927 Gauze Mask to Halt Spread of Plague (Spanish flu) - The Washington Times.jpg
| width2            =
| caption2          = In September 1918, the Red Cross recommended two-layer gauze masks to halt the spread of "plague".<ref name=WashTimes_19180927>{{cite news |title=Gauze Mask to Halt Spread of Plague |url=https://newspaperarchive.com/washington-times-sep-27-1918-p-3/ |work=The Washington Times |date=27 September 1918 |page=3 |access-date=5 October 2020 |archive-date=8 October 2020 |archive-url=https://web.archive.org/web/20201008051659/https://newspaperarchive.com/washington-times-sep-27-1918-p-3/ |url-status=live }}</ref>
| image3            = 1918 Headlines from Chicago newspapers - Spanish flu - 1918 influenza pandemic.jpg
| caption3          = 1918 Chicago newspaper headlines reflect mitigation strategies such as increased ventilation, arrests for not wearing face masks, sequenced [[inoculation]]s, limitations on crowd size, selective closing of businesses, curfews, and lockdowns.<ref name=USAtoday_20201122/> After October's strict containment measures showed some success, Armistice Day celebrations in November and relaxed attitudes by Thanksgiving caused a resurgence.<ref name=USAtoday_20201122>{{cite news | vauthors = Hauck G, Gellis K |title=We're celebrating Thanksgiving amid a pandemic. Here's how we did it in 1918 – and what happened next |url=https://www.usatoday.com/in-depth/news/nation/2020/11/21/covid-and-thanksgiving-how-we-celebrated-during-1918-flu-pandemic/6264231002/ |work=USA Today |date=22 November 2020 |archive-url=https://web.archive.org/web/20201121183814/https://eu.usatoday.com/in-depth/news/nation/2020/11/21/covid-and-thanksgiving-how-we-celebrated-during-1918-flu-pandemic/6264231002/ |archive-date=21 November 2020 |url-status=live }}</ref>
| perrow            = 2 / 1
}}

While systems for alerting public health authorities of infectious spread did exist in 1918, they did not generally include influenza, leading to a delayed response.{{sfn|Spinney|2018|pp=83–84}} Nevertheless, actions were taken. Maritime quarantines were declared on islands such as Iceland, Australia, and American Samoa, saving many lives.{{sfn|Spinney|2018|pp=83–84}} [[Social distancing]] measures were introduced, for example closing schools, theatres, and places of worship, limiting public transportation, and banning mass gatherings.{{sfn|Spinney|2018|pp=87–88}} Wearing [[Surgical mask|face masks]] became common in some places, such as Japan, though there were debates over their efficacy.{{sfn|Spinney|2018|pp=87–88}}<ref>{{cite book |last1=Segrave |first1=Kerry |title=Masking America, 1918–1919: Efforts to Control the Great Influenza Pandemic |date=2024 |publisher=McFarland and Co. |location=Jefferson, NC |isbn=978-1-4766-9449-8 |url=https://mcfarlandbooks.com/product/masking-america-1918-1919 |access-date=1 September 2024 |archive-date=1 September 2024 |archive-url=https://web.archive.org/web/20240901234543/https://mcfarlandbooks.com/product/masking-america-1918-1919/ |url-status=live }}</ref> There was also some resistance to their use, as exemplified by the [[Anti-Mask League of San Francisco]]. Vaccines were developed, but as these were based on bacteria and not the actual virus, they could only help with secondary infections.{{sfn|Spinney|2018|pp=87–88}} The enforcement of restrictions varied.{{sfn|Spinney|2018|p=91}} To a large extent, the New York City health commissioner ordered businesses to open and close on staggered shifts to avoid overcrowding on the subways.<ref>{{Cite web|date=20 September 2021|title=How NYC beat deadly 1918 flu without vaccines, lockdowns, mask mandates or school closures|url=https://www.silive.com/news/2021/09/how-nyc-beat-deadly-1918-flu-without-vaccines-lockdowns-mask-mandates-or-school-closures.html|access-date=23 September 2021|website=silive|language=en|archive-date=21 September 2021|archive-url=https://web.archive.org/web/20210921151432/https://www.silive.com/news/2021/09/how-nyc-beat-deadly-1918-flu-without-vaccines-lockdowns-mask-mandates-or-school-closures.html|url-status=live}}</ref>
A later study found that measures such as banning mass gatherings and requiring the wearing of face masks could cut the death rate up to 50 percent, but this was dependent on their being imposed early in the outbreak and not being lifted prematurely.<ref>{{cite journal | vauthors = Bootsma MC, Ferguson NM | title = The effect of public health measures on the 1918 influenza pandemic in U.S. cities | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 104 | issue = 18 | pages = 7588–7593 | date = May 2007 | pmid = 17416677 | pmc = 1849868 | doi = 10.1073/pnas.0611071104 | s2cid = 11280273 | doi-access = free | bibcode = 2007PNAS..104.7588B }}</ref>

===Medical treatment===
As there were no [[antiviral drug]]s to treat the virus, and no [[antibiotic]]s to treat the secondary bacterial infections, doctors would rely on an assortment of medicines with varying degrees of effectiveness, such as [[aspirin]], [[quinine]], [[arsenic]]s, [[digitalis]], [[strychnine]], [[Magnesium sulfate|epsom salts]], [[castor oil]], and [[iodine]].{{sfn|Spinney|2018|pp=109–10}} [[traditional medicine|Traditional treatments]], such as [[bloodletting]], [[ayurveda]], and [[kampo]], were also applied.{{sfn|Spinney|2018|pp=111–12}}

===Information dissemination===
Due to [[World War I]], many countries engaged in wartime censorship, and suppressed reporting of the pandemic.<ref>{{cite journal | vauthors = Flecknoe D, Charles Wakefield B, Simmons A | title = Plagues & wars: the 'Spanish Flu' pandemic as a lesson from history | journal = Medicine, Conflict and Survival | volume = 34 | issue = 2 | pages = 61–68 | date = June 2018 | pmid = 29764189 | doi = 10.1080/13623699.2018.1472892 | s2cid = 21694687 }}</ref> For example, the Italian newspaper ''[[Corriere della Sera]]'' was prohibited from reporting daily death tolls.{{sfn|Spinney|2018|p=92}} The newspapers of the time were also generally [[Paternalism|paternalistic]] and worried about mass panic.{{sfn|Spinney|2018|p=92}} [[Misinformation]] also spread along with the disease. In Ireland there was a belief that [[Miasma theory|noxious gases]] were rising from the mass graves of [[Flanders Fields]] and being "blown all over the world by winds".{{sfn|Spinney|2018|p=69}} There were also rumors that the Germans were behind it, for example by poisoning the [[aspirin]] manufactured by [[Bayer]], or by [[Chemical weapons in World War I|releasing poison gas]] from [[U-boat]]s.{{sfn|Spinney|2018|p=70}}

==Mortality==
{{see also|List of Spanish flu cases}}
[[File:W curve.png|thumb|Difference between the flu mortality age-distributions of the 1918 pandemic and normal epidemics – deaths per 100,000 persons in each age group, United States, for the interpandemic years 1911–1917 (dashed line) and the pandemic year 1918 (solid line){{sfn|Taubenberger|Morens|2006|p=19}}]]
[[File:1918 spanish flu waves.gif|thumb|upright=1|Three pandemic waves: weekly combined flu and pneumonia mortality, United Kingdom, 1918–1919{{sfn|Taubenberger|Morens|2006|p=17}}]]
The Spanish flu infected around 500 million people, about one-third of the world's population.{{sfn|Taubenberger|Morens|2006}} Estimates on deaths vary greatly, but it is considered to be one of the [[List of pandemics|deadliest pandemics]] in history.<ref>{{cite journal | title = Ten things you need to know about pandemic influenza (update of 14 October 2005) | journal = Relevé Épidémiologique Hebdomadaire | volume = 80 | issue = 49–50 | pages = 428–431 | date = December 2005 | pmid = 16372665 | url = https://apps.who.int/iris/bitstream/handle/10665/232955/WER8049_50_428-431.PDF | access-date = 11 March 2020 | url-status = live | archive-url = https://web.archive.org/web/20210727045636/https://apps.who.int/iris/bitstream/handle/10665/232955/WER8049_50_428-431.PDF | archive-date = 27 July 2021 | vauthors = World Health O }}</ref><ref>{{cite book | vauthors = Jilani TN, Jamil RT, Siddiqui AH | chapter-url = https://www.ncbi.nlm.nih.gov/books/NBK513241/ | chapter = H1N1 Influenza (Swine Flu) |date= 14 December 2019 |pmid=30020613 | title = StatPearls | place = Treasure Island, FL | publisher = StatPearls | via = [[National Center for Biotechnology Information|NCBI]] |access-date=11 March 2020 |archive-url=https://web.archive.org/web/20200312134634/https://www.ncbi.nlm.nih.gov/books/NBK513241/ |archive-date=12 March 2020 |url-status=live }}</ref> An early estimate from 1927 put global mortality at 21.6 million.<ref name="pmid30202996"/> An estimate from 1991 states that the virus killed between 25 and 39 million people.{{sfn|Patterson|Pyle|1991}} A 2005 estimate put the death toll at 50 million, and possibly as high as 100 million.{{sfn|Knobler|2005}}{{sfn|Johnson|Mueller|2002}} However, a 2018 reassessment in the ''[[American Journal of Epidemiology]]'' estimated the total to be about 17 million,<ref name="pmid30202996">{{cite journal | vauthors = Spreeuwenberg P, Kroneman M, Paget J | title = Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic | journal = American Journal of Epidemiology | volume = 187 | issue = 12 | pages = 2561–2567 | date = December 2018 | pmid = 30202996 | pmc = 7314216 | doi = 10.1093/aje/kwy191 | publisher = [[Oxford University Press]] }}</ref> though this has been contested.<ref>{{cite journal | vauthors = Chandra S, Christensen J | title = Re: "Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic" | journal = American Journal of Epidemiology | volume = 188 | issue = 7 | pages = 1404–1406 | date = July 2019 | pmid = 30824934 | doi = 10.1093/aje/kwz044 }} and response {{cite journal | vauthors = Spreeuwenberg P, Kroneman M, Paget J | title = The Authors Reply | journal = American Journal of Epidemiology | volume = 188 | issue = 7 | pages = 1405–1406 | date = July 2019 | pmid = 30824908 | doi = 10.1093/aje/kwz041 | url = https://postprint.nivel.nl/PPpp7146.pdf | access-date = 12 March 2020 | url-status = dead | archive-url = https://web.archive.org/web/20200312204122/https://postprint.nivel.nl/PPpp7146.pdf | archive-date = 12 March 2020 }}</ref> Estimates done in 2021 by [[John M. Barry]] have the total death toll alone at well above 100 million.<ref name=":1" /> With a world population of 1.8 to 1.9 billion,<ref>{{cite web |title=Historical Estimates of World Population |url=https://www.census.gov/population/international/data/worldpop/table_history.php |archive-url=https://web.archive.org/web/20120709092946/https://www.census.gov/population/international/data/worldpop/table_history.php |url-status=dead |archive-date=9 July 2012 |access-date=29 March 2013}}</ref> these estimates correspond to between 1 and 6 percent of the population.{{cn|date=May 2025}}

A 2009 study in ''[[Influenza and Other Respiratory Viruses]]'' based on data from fourteen European countries estimated a total of 2.64 million excess deaths in Europe attributable to the Spanish flu during the 1918–1919 phase of the pandemic. This represents a mortality rate of about 1.1% of the European population ({{circa}} 250 million in 1918), considerably higher than the mortality rate in the U.S., which the authors hypothesize is likely due to the severe effects of the war in Europe.<ref name="IORV2009"/> The excess mortality rate in the U.K. has been estimated at 0.28%–0.4%, far below this European average.<ref name="pmid30202996"/>

Some 12–17 million people died in [[1918 flu pandemic in India|India]], about 5% of the population.<ref>{{cite journal | vauthors = Mayor S | title = Flu experts warn of need for pandemic plans | journal = BMJ | volume = 321 | issue = 7265 | pages = 852 | date = October 2000 | pmid = 11021855 | pmc = 1118673 | doi = 10.1136/bmj.321.7265.852 }}</ref> The death toll in [[British Raj|India's British-ruled districts]] was 13.88 million.{{sfn|Chandra|Kuljanin|Wray|2012}} Another estimate gives at least 12 million dead.<ref>{{cite journal | vauthors = Arnold D | title = Death and the Modern Empire: The 1918–19 Influenza Epidemic in India. | journal = Transactions of the Royal Historical Society | date = December 2019 | volume = 29 | pages = 181–200 | doi = 10.1017/S0080440119000082 }}</ref> The decade between 1911 and 1921 was the only census period in which India's population fell, mostly due to devastation of the pandemic.<ref>{{Cite web|url=https://www.livemint.com/news/world/why-1918-matters-in-india-s-corona-war-11584033795146.html|title=Why 1918 matters in India's corona war | vauthors = Sreevatsan A |date=12 March 2020|website=mint|access-date=7 June 2020|archive-date=18 April 2020|archive-url=https://web.archive.org/web/20200418110954/https://www.livemint.com/news/world/why-1918-matters-in-india-s-corona-war-11584033795146.html|url-status=live}}</ref><ref>{{Cite web|url=https://www.hindustantimes.com/analysis/what-the-history-of-pandemics-tells-us-about-coronavirus/story-Fb3XDfXe0lyk0JukqtdG1L.html|title=What the history of pandemics tells us about coronavirus|date=15 April 2020|website=Hindustan Times|access-date=7 June 2020|archive-date=21 April 2020|archive-url=https://web.archive.org/web/20200421154324/https://www.hindustantimes.com/analysis/what-the-history-of-pandemics-tells-us-about-coronavirus/story-Fb3XDfXe0lyk0JukqtdG1L.html|url-status=live}}</ref> While India is generally described as the country most severely affected by the Spanish flu, at least one study argues that other factors may partially account for the very high excess mortality rates observed in 1918, citing unusually high 1917 mortality and wide regional variation (ranging from 0.47% to 6.66%).<ref name="pmid30202996"/> A 2006 study in ''[[The Lancet]]'' also noted that Indian provinces had excess mortality rates ranging from 2.1% to 7.8%, stating: "Commentators at the time attributed this huge variation to differences in nutritional status and diurnal fluctuations in temperature."<ref name="Lancet 2006 Murray, Lopez, Chin, Feehan">{{cite journal | vauthors = Murray CJ, Lopez AD, Chin B, Feehan D, Hill KH | title = Estimation of potential global pandemic influenza mortality on the basis of vital registry data from the 1918-20 pandemic: a quantitative analysis | journal = Lancet | volume = 368 | issue = 9554 | pages = 2211–2218 | date = December 2006 | pmid = 17189032 | doi = 10.1016/S0140-6736(06)69895-4 | url = https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(06)69895-4/fulltext | access-date = 30 September 2020 | publisher = [[Elsevier]] | url-status = live | s2cid = 22787011 | archive-url = https://web.archive.org/web/20200927235224/https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(06)69895-4/fulltext | archive-date = 27 September 2020 | url-access = subscription }}</ref>

In Finland, 20,000 died out of 210,000 infected.<ref>{{Cite web|title=Historiallisia Papereita 1|issn=1456-8055|url=http://historiallinenyhdistys.fi/muinaiset_sivut/julk/taudit99/|access-date=24 June 2020|website=historiallinenyhdistys.fi|archive-date=6 February 2020|archive-url=https://web.archive.org/web/20200206132858/http://historiallinenyhdistys.fi/muinaiset_sivut/julk/taudit99/|url-status=live}}</ref> In Sweden, 34,000 died.<ref>{{Cite book| vauthors = Åman M |title=Spanska sjukan: den svenska epidemin 1918–1920 och dess internationella bakgrund|date=1990|publisher=Ubsaliensis Academiae; Distributor, Almqvist & Wiksell International|isbn=978-91-554-2587-6|place=Uppsala; Stockholm|language=sv|oclc=22451542}}</ref>

In Japan, the flu killed nearly 500,000 people over two waves between 1918 and 1920, with nearly 300,000 excess deaths between October 1918 and May 1919 and 182,000 between December 1919 and May 1920.<ref name="World Health Organization-2013"/>

In the [[Dutch East Indies]] (now [[Indonesia]]), 1.5 million were assumed to have died among 30 million inhabitants.<ref>{{cite web | vauthors = Fitri E | title = Looking Through Indonesia's History For Answers to Swine Flu | url = http://thejakartaglobe.com/home/looking-through-indonesias-history-for-answers-to-swine-flu/337976 | archive-url = https://web.archive.org/web/20091102151942/http://thejakartaglobe.com/home/looking-through-indonesias-history-for-answers-to-swine-flu/337976 | archive-date = 2 November 2009 | work = The Jakarta Globe | date = 28 October 2009 | access-date = 28 March 2017 | url-status = dead }}</ref> In [[Tahiti]], 13% of the population died in one month. Similarly, in [[Western Samoa Trust Territory|Western Samoa]] 22% of the population of 38,000 died within two months.{{sfn|Kohn|2007}}

In [[Istanbul]], capital of the Ottoman Empire, 6,403<ref name="İSPANYOL GRİBİNİN DÜNYA VE OSMANLI DEVLETİ ÜZERİNDEKİ ETKİLERİ">{{Cite web|title=İSPANYOL GRİBİNİN DÜNYA VE OSMANLI DEVLETİ ÜZERİNDEKİ ETKİLERİ|url=http://www.cihanharbi.com/ispanyol-gribinin-dunya-ve-osmanli-devleti-uzerindeki-etkileri-the-impact-of-spanish-influenza-on-the-world-and-the-ottoman-empire/|access-date=2 November 2020|language=tr-TR|archive-date=8 November 2020|archive-url=https://web.archive.org/web/20201108054237/http://www.cihanharbi.com/ispanyol-gribinin-dunya-ve-osmanli-devleti-uzerindeki-etkileri-the-impact-of-spanish-influenza-on-the-world-and-the-ottoman-empire/|url-status=live}}</ref> to 10,000<ref name="www.sozcu.com.tr"/> died, giving the city a mortality rate of at least 0.56%.<ref name="İSPANYOL GRİBİNİN DÜNYA VE OSMANLI DEVLETİ ÜZERİNDEKİ ETKİLERİ"/>

In New Zealand, the flu killed an estimated 6,400 {{lang|mi|[[Pākehā]]}} (or "New Zealanders primarily of European descent") and 2,500 [[Māori people|Māori]] in six weeks, with Māori dying at eight times the rate of {{lang|mi|Pākehā}}.<ref>{{Cite web |url=https://www.noted.co.nz/health/1918-flu-centenary-how-to-survive-a-pandemic/ |title=1918 flu centenary: How to survive a pandemic|access-date=19 June 2019 |archive-url=https://web.archive.org/web/20190709072615/https://www.noted.co.nz/health/1918-flu-centenary-how-to-survive-a-pandemic/ |archive-date=9 July 2019 |url-status=live}}</ref><ref>{{Cite book |title=Black November: the 1918 influenza pandemic in New Zealand | vauthors = Rice G, Bryder L |isbn=978-1-927145-91-3 |edition=Second, revised and enlarged |place=Christchurch, NZ |oclc=960210402}}</ref>

In Australia, the flu killed around 12,000<ref name="VojnosanitetskiPregled">{{cite journal | vauthors = Radusin M | title = The Spanish flu – part II: the second and third wave | journal = Vojnosanitetski Pregled | volume = 69 | issue = 10 | pages = 917–927 | date = October 2012 | pmid = 23155616 | url = https://www.rastko.rs/cms/files/books/5218e8f259be8 | url-status = live | access-date = 23 April 2020 | archive-url = https://web.archive.org/web/20200709205413/https://www.rastko.rs/cms/files/books/5218e8f259be8 | archive-date = 9 July 2020 }}</ref> to 20,000 people.<ref name="vicparl">{{cite web |date=23 April 2020 |title=Epidemics and pandemics in Victoria: Historical perspectives |url=https://www.parliament.vic.gov.au/publications/research-papers/download/36-research-papers/13957-epidemics-and-pandemics-in-victoria-historical-perspectives |access-date=14 September 2022 |website=[[Parliament of Victoria]] |archive-date=14 September 2022 |archive-url=https://web.archive.org/web/20220914060458/https://www.parliament.vic.gov.au/publications/research-papers/download/36-research-papers/13957-epidemics-and-pandemics-in-victoria-historical-perspectives |url-status=live }}</ref> The country's death rate, 2.7 per 1,000 people, was one of the lowest recorded; however, as much as 40 percent of the population were infected, and a mortality rate of 50 percent was recorded by some [[Aboriginal Australian|Aboriginal]] communities.<ref name="nma">{{cite web |title=Influenza pandemic |url=https://www.nma.gov.au/defining-moments/resources/influenza-pandemic |access-date=14 September 2022 |website=[[National Museum of Australia]] |archive-date=14 September 2022 |archive-url=https://web.archive.org/web/20220914060440/https://www.nma.gov.au/defining-moments/resources/influenza-pandemic |url-status=live }}</ref><ref name="vicparl"/> New South Wales and Victoria saw the greatest relative mortality, with 3.19 and 2.40 deaths per 1,000 people respectively, while Western Australia, Queensland, Southern Australia, and Tasmania experienced rates of 1.70, 1.14, 1.13, and 1.09 per 1,000 respectively. In Queensland, at least one-third of deaths recorded were in the Aboriginal population.<ref name="Shanks"/>

In the U.S., about 20 million out of a population of 105 million became infected in the 1918–1919 season, and an estimated 500,000 to 850,000 died (0.5 to 0.8 percent of the U.S. population).<ref>{{Cite web | url=https://www.usdeadlyevents.com/1918-1920-influenza-and-pneumonia-pandemic-nationwide-820000-850000/ | title=1918–1920 – Influenza and Pneumonia Pandemic – Nationwide ~820,000–850,000 – Deadliest American Disasters and Large-Loss-of-Life Events | date=January 1918 | access-date=22 May 2020 | archive-date=30 May 2020 | archive-url=https://web.archive.org/web/20200530205216/https://www.usdeadlyevents.com/1918-1920-influenza-and-pneumonia-pandemic-nationwide-820000-850000/ | url-status=live }}</ref><ref>[https://web.archive.org/web/20160923152823/http://www.flu.gov/pandemic/history/1918/ The Great Pandemic:  The United States in 1918–1919], U.S. Department of Health & Human Services.</ref><ref>{{Cite web | url=https://collections.nlm.nih.gov/catalog/nlm:nlmuid-8800017A-vid | title=The silent invader – Digital Collections – National Library of Medicine | access-date=15 April 2020 | archive-date=24 July 2020 | archive-url=https://web.archive.org/web/20200724112317/https://collections.nlm.nih.gov/catalog/nlm:nlmuid-8800017A-vid | url-status=live }}</ref> [[Native Americans in the United States|Native Americans]] tribes were particularly affected. In the [[Four Corners]] area, there were 3,293 registered deaths among Native Americans.<ref>{{cite web |title=Flu Epidemic Hit Utah Hard in 1918, 1919 |website = [[Deseret News]]|url=http://www.deseretnews.com/article/412123/FLU-EPIDEMIC-HIT-UTAH-HARD-IN-1918-1919.html?pg=all |date=28 March 1995 |access-date=7 July 2012 |archive-url=https://web.archive.org/web/20121130180503/http://www.deseretnews.com/article/412123/FLU-EPIDEMIC-HIT-UTAH-HARD-IN-1918-1919.html?pg=all |archive-date=30 November 2012 |url-status=dead }}</ref> Entire [[Inuit]] and [[Alaskan Native]] village communities died in [[Territory of Alaska|Alaska]].<ref>{{cite web |title=The Great Pandemic of 1918: State by State |url=http://www.pandemicflu.gov/general/greatpandemic.html#alaska |archive-url=https://web.archive.org/web/20090506220116/http://www.pandemicflu.gov/general/greatpandemic.html |archive-date=6 May 2009 |url-status=dead |access-date=4 May 2009|date=5 March 2018 }}</ref> In Canada, 50,000 died.<ref>[https://web.archive.org/web/20090809000857/http://history.cbc.ca/history/?MIval=EpisContent.html&series_id=1&episode_id=12&chapter_id=2&page_id=6&lang=E "A deadly virus rages throughout Canada at the end of the First World War"]. CBC History.</ref>

In Brazil, 300,000 died, including president [[Francisco de Paula Rodrigues Alves|Rodrigues Alves]].<ref>{{cite web |title=A gripe espanhola no Brasil&nbsp;– Elísio Augusto de Medeiros e Silva, empresário, escritor e membro da AEILIJ |url=http://jornaldehoje.com.br/a-gripe-espanhola-no-brasil-elisio-augusto-de-medeiros-e-silva-empresario-escritor-e-membro-da-aeilij-elisiomercomix-com-br/ |publisher=Jornal de Hoje |access-date=22 January 2014 |language=pt |archive-url=https://web.archive.org/web/20140202164917/http://jornaldehoje.com.br/a-gripe-espanhola-no-brasil-elisio-augusto-de-medeiros-e-silva-empresario-escritor-e-membro-da-aeilij-elisiomercomix-com-br/ |archive-date=2 February 2014 |url-status=live }}</ref>

In the UK, as many as 250,000 died; in France, more than 400,000.<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/health/4350050.stm |title=The "bird flu" that killed 40&nbsp;million |work=BBC News |date=19 October 2005 |access-date=26 April 2009 |archive-url=https://web.archive.org/web/20171107104411/http://news.bbc.co.uk/2/hi/health/4350050.stm |archive-date=7 November 2017 |url-status=live }}</ref>

In [[Gold Coast (British colony)|Ghana]], the influenza epidemic killed at least 100,000 people.{{sfn|Hays|1998}} [[Haile Selassie of Ethiopia|Tafari Makonnen]] (the future [[Emperor of Ethiopia]]) was one of the first Ethiopians who contracted influenza but survived.<ref name="Marcus">{{cite book | vauthors = Marcus H |title=Haile Sellassie I: The formative years, 1892–1936 |place=Trenton, NJ |publisher=Red Sea Press |year=1996 |pages=36ff}}</ref>{{sfn|Pankhurst|1991|pp=48f}} Estimates for fatalities in the capital city, [[Addis Ababa]], range from 5,000 to 10,000, or higher.{{sfn|Pankhurst|1991|p=63}}

The death toll in [[Russian Soviet Federative Socialist Republic|Russia]] has been estimated at 450,000, though the epidemiologists who suggested this number called it a "shot in the dark".{{sfn|Patterson|Pyle|1991}} If it is correct, Russia lost roughly 0.4% of its population, meaning it suffered the lowest influenza-related mortality in Europe. Another study considers this number unlikely, given that the country was in the grip of a [[civil war]], and the infrastructure of daily life had broken down; the study suggests that Russia's death toll was closer to 2%, or 2.7 million people.{{sfn|Spinney|2018|pp=167–69}}

=== Devastated communities ===
[[File:Spanish flu death chart.png|thumb|upright=1|Deaths from all causes for New York, London, Paris, and Berlin with peaks in October and November 1918]]
Even in areas where mortality was low, so many adults were incapacitated that daily life was hampered. Some communities closed all stores or required customers to leave orders outside. There were reports that healthcare workers could not tend the sick nor the gravediggers bury the dead because they too were ill. Mass graves were dug by [[steam shovel]] and bodies buried without coffins in many places.<ref>{{cite news|date=1 November 2004|title=Viruses of mass destruction|publisher=CNN|url=https://money.cnn.com/magazines/fortune/fortune_archive/2004/11/01/8189572/index.htm|url-status=live|access-date=30 April 2009|archive-url=https://web.archive.org/web/20090506053835/http://money.cnn.com/magazines/fortune/fortune_archive/2004/11/01/8189572/index.htm|archive-date=6 May 2009|series=Fortune}}</ref>

[[Bristol Bay]], a region of Alaska populated by [[Alaska Natives|Indigenous people]], suffered a death rate of 40 percent, with some villages entirely disappearing.{{sfn|Spinney|2018|p=134}} [[Nenana, Alaska]], avoided the extent of the pandemic between 1918 and 1919, but the flu at last reached the town in spring 1920. Reports suggested that during the first two weeks of May, the majority of the town's population became infected; 10% of the population were estimated to have died, most of whom were Alaska Natives.<ref>{{Cite web |date=27 October 2021 |title=The Flu Pandemic hit Nenana 100 Years Ago |url=https://www.nps.gov/articles/dena-history-pandemic.htm |access-date=12 April 2022 |website=nps.gov |archive-date=13 April 2022 |archive-url=https://web.archive.org/web/20220413025708/https://www.nps.gov/articles/dena-history-pandemic.htm |url-status=live }}</ref>

Several [[Pacific island]] territories were hit particularly hard. The pandemic reached them from New Zealand, which was too slow to implement measures to prevent ships carrying the flu from leaving its ports. From New Zealand, the flu reached [[Tonga]] (killing 8% of the population), [[Nauru]] (16%), and [[Colony of Fiji|Fiji]] (5%, 9,000&nbsp;people).{{sfn|Denoon|2004}} Worst affected was Western Samoa, which had been [[Occupation of German Samoa|occupied by New Zealand]] in 1914. 90% of the population was infected; 30% of adult men, 22% of adult women, and 10% of children died.{{sfn|Denoon|2004}} The disease spread fastest through the higher social classes among the Indigenous peoples, because of the custom of gathering [[oral tradition]] from chiefs on their deathbeds; many community elders were infected through this process.<ref>{{Cite journal| vauthors = Wishart S |date=July–August 2018|title=How the 1918 flu spread|url=https://www.nzgeo.com/stories/how-the-1918-flu-spread/|url-status=live|journal=New Zealand Geographic|issue=152|page=23|archive-url=https://web.archive.org/web/20180803074604/https://www.nzgeo.com/stories/how-the-1918-flu-spread/|archive-date=3 August 2018|access-date=3 August 2018}}</ref>

In [[Qajar Iran|Iran]], the mortality was estimated at between 902,400 and 2,431,000, or 8% to 22% of the total population.{{Sfnm|1a1=Afkhami|1y=2003|2a1=Afkhami|2y=2012}} The country was going through the [[Persian famine of 1917–1919]] concurrently.

In [[History of Ireland (1801–1923)|Ireland]], during the worst 12 months, the Spanish flu accounted for one-third of all deaths.<ref>{{Cite news|vauthors=FitzGerald J|title=Coronavirus: forgotten lessons of the Spanish flu pandemic|url=https://www.irishtimes.com/business/economy/coronavirus-forgotten-lessons-of-the-spanish-flu-pandemic-1.4234270|access-date=14 June 2020|newspaper=The Irish Times|quote=Yet the "Spanish" flu epidemic of 1918–19 resulted in about 25,000 extra deaths in Ireland, many of them young adults. This was almost as many deaths as occurred among the Irish fighting in the First World War.|archive-date=5 May 2020|archive-url=https://web.archive.org/web/20200505231059/https://www.irishtimes.com/business/economy/coronavirus-forgotten-lessons-of-the-spanish-flu-pandemic-1.4234270|url-status=live}}</ref><ref>{{Cite web|title=Official Ireland Statistics Office|url=https://www.cso.ie/en/releasesandpublications/ep/p-1916/1916irl/bmd/deaths/|access-date=14 June 2020|website=Central Statistics Office Ireland|quote=Total deaths in Ireland 1916: 50,627|archive-date=14 June 2020|archive-url=https://web.archive.org/web/20200614193849/https://www.cso.ie/en/releasesandpublications/ep/p-1916/1916irl/bmd/deaths/|url-status=live}}</ref>

In South Africa it is estimated that about 300,000 people amounting to 6% of the population died within six weeks. Government actions in the early stages of the virus' arrival in the country in September 1918 are believed to have unintentionally accelerated its spread.<ref>{{Cite web|vauthors=Phillips H|title=South Africa bungled the Spanish flu in 1918. History mustn't repeat itself for COVID-19|url=http://theconversation.com/south-africa-bungled-the-spanish-flu-in-1918-history-mustnt-repeat-itself-for-covid-19-133281|access-date=26 May 2020|website=The Conversation|date=10 March 2020 |archive-date=13 June 2020|archive-url=https://web.archive.org/web/20200613084500/https://theconversation.com/south-africa-bungled-the-spanish-flu-in-1918-history-mustnt-repeat-itself-for-covid-19-133281|url-status=live}}</ref> Almost a quarter of the working population of [[Kimberley, Northern Cape|Kimberley]], consisting of workers in the diamond mines, died.{{sfn|Spinney|2018|p=72}} In [[British Somaliland]], one official estimated that 7% of the native population died.{{sfn|Pankhurst|1991|pp=51ff}} This huge death toll resulted from an extremely high [[infection rate]] of up to 50% and the extreme severity of the symptoms.{{sfn|Patterson|Pyle|1991}}

=== Other areas ===
In the Pacific, American Samoa<ref name="usnavyreport">{{cite web|title=Influenza of 1918 (Spanish Flu) and the US Navy|url=http://www.history.navy.mil/library/online/influenza_main.htm|url-status=dead|archive-url=http://webarchive.loc.gov/all/20150111194407/http://www.history.navy.mil/library/online/influenza_main.htm|archive-date=11 January 2015|access-date=14 May 2009|website=history.navy.mil}}</ref> and the French colony of [[New Caledonia]]<ref name="whoreport">{{cite journal | vauthors = Bell D, Nicoll A, Fukuda K, Horby P, Monto A, Hayden F, Wylks C, Sanders L, Van Tam J | title = Non-pharmaceutical interventions for pandemic influenza, international measures | journal = Emerging Infectious Diseases | volume = 12 | issue = 1 | pages = 81–87 | date = January 2006 | pmid = 16494722 | pmc = 3291414 | doi = 10.3201/eid1201.051370 }}</ref> succeeded in preventing even a single death from influenza through effective [[quarantine]]s. However, the outbreak was delayed into 1926 for American Samoa and 1921 for New Caledonia as the quarantine period ended.<ref name="Shanks-2013">{{cite journal | vauthors = Shanks GD, Brundage JF | title = Pacific islands which escaped the 1918–1919 influenza pandemic and their subsequent mortality experiences | journal = Epidemiology and Infection | volume = 141 | issue = 2 | pages = 353–356 | date = February 2013 | pmid = 22564320 | pmc = 9152047 | doi = 10.1017/S0950268812000866 | s2cid = 23794327 }}</ref> On American Samoa, at least 25% of the island residents were clinically attacked and 0.1% died, and on New Caledonia, there was widespread illness and 0.1% population died.<ref name="Shanks-2013" /> Australia also managed to avoid the first two waves with a quarantine.{{sfn|Spinney|2018|pp=83–84}} Iceland protected a third of its population from exposure by blocking the main road of the island.{{sfn|Spinney|2018|pp=83–84}} By the end of the pandemic, the isolated island of [[Marajó]], in Brazil's Amazon River Delta had not reported an outbreak.<ref>{{cite book |title=Pandemic Influenza: Emergency planning and community preparedness |publisher=CRC Press |year=2009 | veditors = Ryan J |place=Boca Raton, FL |page=24}}</ref> [[Saint Helena]] also reported no deaths.<ref>"Colonial Annual Report", 1919</ref>

[[File:1919FluVictimsTokyo.jpg|thumb|Japanese women in Tokyo during the Spanish flu pandemic, 1919]]
Estimates for the death toll in China have varied widely,<ref name="ijima">{{cite book|title=The Spanish Flu Pandemic of 1918: New Perspectives|vauthors=Iijima W|publisher=Routledge|year=2003|veditors=Phillips H, Killingray D|place=London and New York|pages=101–09|article=Spanish influenza in China, 1918–1920: a preliminary probe}}</ref>{{sfn|Patterson|Pyle|1991}} reflecting the lack of centralized collection of health data at the time due to the [[Warlord Era|Warlord period]]. China may have experienced a relatively mild flu season in 1918 compared to other areas of the world.<ref name="Cheng_2007"/><ref name="Saunders-Hastings_2016"/><ref>{{Cite book |vauthors=Killingray D, Phillips H |url=https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37 |title=The Spanish Influenza Pandemic of 1918–1919: New Perspectives |year=2003 |publisher=Routledge |isbn=978-1-134-56640-2 |access-date=9 November 2020 |archive-date=27 July 2021 |archive-url=https://web.archive.org/web/20210727045645/https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37 |url-status=live }}</ref> However, some reports from its interior suggest that mortality rates from influenza were perhaps higher in at least a few locations in 1918.{{sfn|Spinney|2018|pp=167–69}} At the very least, there is little evidence that China as a whole was seriously affected by the flu compared to other countries.<ref>{{Cite book |vauthors=Killingray D, Phillips H |url=https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37 |title=The Spanish Influenza Pandemic of 1918–1919: New Perspectives |publisher=Routledge |year=2003 |isbn=978-1-134-56640-2 |access-date=9 November 2020 |archive-date=27 July 2021 |archive-url=https://web.archive.org/web/20210727045657/https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37 |url-status=live }}</ref>

The first estimate of the Chinese death toll was made in 1991 by Patterson and Pyle, which estimated a toll of between 5 and 9 million. However, this study was criticized by later studies due to flawed methodology, and newer studies have published estimates of a far lower mortality rate in China.<ref name="Killingray-2003"/><ref>{{Cite book | vauthors = Iijima W | title = The Spanish influenza in China, 1918–1920 | date = 1998 | oclc = 46987588 }}</ref> For instance, Iijima in 1998 estimates the death toll in China to be between 1 and 1.28 million based on data available from Chinese port cities.<ref>{{Cite conference |vauthors=Iijima W |date=1998 |title=The Spanish influenza in China, 1918–1920 |url=https://searchworks.stanford.edu/view/5409238 |conference=Spanish 'Flu 1918–1998: Reflections on the Influenza Pandemic of 1918 after 80 Years |place=Cape Town, South Africa |access-date=11 April 2020 |archive-date=11 April 2020 |archive-url=https://web.archive.org/web/20200411171040/https://searchworks.stanford.edu/view/5409238 |url-status=live }}</ref> The lower estimates of the Chinese death toll are based on the low mortality rates that were found in Chinese port cities and on the assumption that poor communications prevented the flu from penetrating the interior of China.<ref name="ijima"/> However, some contemporary newspaper and post office reports, as well as reports from missionary doctors, suggest that the flu did penetrate the Chinese interior and that influenza was severe in at least some locations in the countryside of China.{{sfn|Spinney|2018|pp=167–69}}

Although medical records from China's interior are lacking, extensive medical data were recorded in Chinese port cities, such as then [[British Empire|British]]-controlled Hong Kong, [[Guangzhou|Canton]], [[Beijing|Peking]], [[Harbin]] and [[Shanghai]]. These data were collected by the [[Chinese Maritime Customs Service]], which was largely staffed by non-Chinese foreigners.<ref name="Killingray_2003">{{Cite book|url=https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37|title=The Spanish Influenza Pandemic of 1918–1919: New Perspectives|vauthors=Killingray D, Phillips H|publisher=Routledge|year=2003|isbn=978-1-134-56640-2|pages=105|access-date=9 November 2020|archive-date=27 July 2021|archive-url=https://web.archive.org/web/20210727045638/https://books.google.com/books?id=k79_8QX8n44C&q=spanish+flu+china+ports+18+million+india&pg=PT37|url-status=live}}</ref> As a whole, data from China's port cities show low mortality rates compared to other cities in Asia.<ref name="Killingray_2003"/> For example, the British authorities at Hong Kong and Canton reported a mortality rate from influenza at a rate of 0.25% and 0.32%, much lower than the reported mortality rate of other cities in Asia, such as [[Kolkata|Calcutta]] or Bombay, where influenza was much more devastating.<ref name="Killingray_2003"/> Similarly, in the city of [[Shanghai]] – which had a population of over 2 million – there were only 266 recorded deaths from [[influenza]] among the Chinese population in 1918.<ref name="Killingray_2003"/> If extrapolated from the extensive data recorded from Chinese cities, the suggested mortality rate from influenza in China as a whole in 1918 was likely lower than 1% – much lower than the world average (which was around 3–5%).<ref name="Killingray_2003"/> In contrast, Japan and Taiwan had reported a mortality rate from influenza around 0.45% and 0.69% respectively, higher than the mortality rate collected from data in Chinese port cities, such as Hong Kong (0.25%), Canton (0.32%), and Shanghai.<ref name="Killingray_2003"/>

However, the influenza mortality rate in Hong Kong and Canton are under-recorded, because only the deaths that occurred in colony hospitals were counted.<ref name="Killingray_2003" /> Similarly, in Shanghai, these statistics are limited to that area of the city under the control of the health section of the Shanghai International Settlement; the actual death toll in Shanghai was much higher.<ref name="Killingray_2003" /> The medical records from China's interior indicate that, compared to cities, rural communities have substantially higher mortality rate.<ref>{{cite journal | vauthors = Alita XP, Ling T, Bin ZH, Xiao-ting LI | title = Epidemic analysisi of 1918 Spanish influenza in China based on literatures. | journal = Journal of Medical Informatics | date = 2010 | volume = 31 | issue = 1 | pages = 47–50 | url = https://en.cnki.com.cn/Article_en/CJFDTotal-YXQB201001015.htm | access-date = 29 July 2021 | archive-date = 29 July 2021 | archive-url = https://web.archive.org/web/20210729164632/https://en.cnki.com.cn/Article_en/CJFDTotal-YXQB201001015.htm | url-status = dead }}</ref> A published influenza survey in Houlu County, Hebei Province, found that the case fatality rate was 9.77% and 0.79% of county population died from influenza in October and November 1918.<ref>{{Cite journal| vauthors = Hong NH |date=2015|title=Epidemic Analysis of 1918 Influenza in China – Research on Huolu County in Zhili Province|journal=Historical Research in Auhui | url = }}</ref>

===Patterns of fatality===
[[File:1918 at Spanish Flu Ward Walter Reed (cropped).jpg|thumb|A nurse wears a cloth face mask while treating a flu patient in Washington, DC, c. 1919]]
The pandemic mostly killed young adults. In 1918–1919, 99% of pandemic influenza deaths in the U.S. occurred in people under 65, and nearly half of deaths were in young adults 20 to 40 years old. In 1920, the mortality rate among people under 65 had decreased sixfold to half the mortality rate of people over 65, but 92% of deaths still occurred in people under 65.{{sfn|Simonsen|Clarke|Schonberger|Arden|1998}} This is unusual since influenza is typically most deadly to weak individuals, such as [[infant]]s under age two, adults over age 70, and the [[immunocompromise]]d. In 1918, older adults may have had partial protection caused by exposure to the 1889–1890 flu pandemic.<ref name=hansen>{{cite book | vauthors = Hanssen O | title = Undersøkelser over influenzaens optræden specielt i Bergen 1918–1922 | trans-title = Investigations into the appearance of influenza, especially in Bergen 1918–1922) | language = Norwegian | publisher = Grieg | date = 1923 | series = Skrifter utgit av Klaus Hansens fond, nr. III. Bergen: Haukeland Sykehus, 1923 (Writings published by the Klaus Hansen Foundation, No. III, Haukeland Hospital Bergen | page = 66 }}</ref> According to historian John M. Barry, the most vulnerable of all were pregnant women. He reported that in thirteen studies of hospitalized women in the pandemic, the death rate ranged from 23% to 71%.<ref>{{cite web |vauthors=Knobler SL, Mack A, Mahmoud A, Lemon SM |title=Institute of Medicine (US) Forum on Microbial Threats |url=https://www.ncbi.nlm.nih.gov/books/NBK22148/ |publisher=NCBI |access-date=17 August 2021 |archive-date=23 December 2020 |archive-url=https://web.archive.org/web/20201223130139/https://www.ncbi.nlm.nih.gov/books/NBK22148/ |url-status=live }}</ref> Of the pregnant women who survived childbirth, over one-quarter (26%) lost the child.{{sfn|Barry|2004|p=239}} Another oddity was that the outbreak was widespread in the summer and autumn (in the Northern Hemisphere); influenza is usually worse in winter.<ref>{{cite web |title=Key Facts about Swine Influenza | work = U.S. Centers for Disease Control and Prevention |url=https://www.cdc.gov/flu/swineflu/keyfacts_pigs.htm |access-date=30 April 2009 |archive-url=https://web.archive.org/web/20090505011201/http://www.cdc.gov/h1n1flu/key_facts.htm |url-status=live |archive-date=5 May 2009}}</ref>

There were also geographic patterns to the disease's fatality. Some parts of Asia had 30 times higher death rates than some parts of Europe, and generally, Africa and Asia had higher rates, while Europe and North America had lower ones.{{sfn|Spinney|2018|pp=180–82}} There was also great variation within continents, with three times higher mortality in Hungary and Spain compared to Denmark, two to three times higher chance of death in Sub-Saharan Africa compared to North Africa, and possibly up to ten times higher rates between the extremes of Asia.{{sfn|Spinney|2018|pp=180–82}} Cities were affected worse than rural areas.{{sfn|Spinney|2018|pp=180–82}} There were also differences between cities, which might have reflected exposure to the milder first wave giving immunity, as well as the introduction of social distancing measures.{{sfn|Spinney|2018|pp=183–84}}

Another major pattern was the differences between social classes. In [[Oslo]], death rates were inversely correlated with apartment size, as the poorer people living in smaller apartments died at a higher rate.<ref>{{cite journal | vauthors = Mamelund SE | title = A socially neutral disease? Individual social class, household wealth and mortality from Spanish influenza in two socially contrasting parishes in Kristiania 1918–19 | journal = Social Science & Medicine | volume = 62 | issue = 4 | pages = 923–940 | date = February 2006 | pmid = 16084634 | doi = 10.1016/j.socscimed.2005.06.051 }}</ref> Social status was also reflected in the higher mortality among immigrant communities, with [[Italian Americans]], a recently arrived group at the time, nearly twice as likely to die compared to the average Americans.{{sfn|Spinney|2018|pp=180–82}} These disparities reflected worse diets, crowded living conditions, and problems accessing healthcare.{{sfn|Spinney|2018|pp=180–82}} Paradoxically, however, [[African Americans]] were relatively spared.{{sfn|Spinney|2018|pp=180–82}}

More men than women were killed by the flu, as they were more likely to go out and be exposed, while women tended to [[Housewife|stay at home]].{{sfn|Spinney|2018|pp=183–84}} For the same reason men also were more likely to have pre-existing [[tuberculosis]], which severely worsened the chances of recovery.{{sfn|Spinney|2018|pp=183–84}} However, in India the opposite was true, potentially because Indian women were neglected with poorer nutrition, and were expected to care for the sick.{{sfn|Spinney|2018|pp=183–84}}

A study conducted by He ''et al''. (2011) examined the factors that underlie variability in temporal patterns and their correlation to patterns of mortality and morbidity. Their analysis suggests that temporal variations in transmission rate provide the best explanation, and the variation in transmission required to generate these three waves is within biologically plausible values.{{sfn|He|Dushoff|Day|Ma|2011}} Another study by He ''et al''. (2013) used a simple [[epidemic model]] incorporating three factors to infer the cause of the three waves of the 1918 influenza pandemic. These factors were school opening and closing, temperature changes throughout the outbreak, and human behavioral changes in response to the outbreak. Their modeling results showed that all three factors are important, but human behavioral responses showed the most significant effects.{{sfn|He|Dushoff|Day|Ma|2013}}

==Effects==
===World War I===
Academic Andrew Price-Smith has argued that the virus helped tip the balance of power in the latter days of the war towards the Allied cause. He provides data that the viral waves hit the [[Central Powers]] before the Allied powers and that [[morbidity]] and mortality in Germany and Austria were considerably higher than in Britain and France.{{sfn|Price-Smith|2008}} A 2006 ''Lancet'' study corroborates higher excess mortality rates in Germany (0.76%) and Austria (1.61%) compared to Britain (0.34%) and France (0.75%).<ref name="Lancet 2006 Murray, Lopez, Chin, Feehan"/>

Kenneth Kahn at [[Oxford University Computing Services]] writes that "Many researchers have suggested that the conditions of the war significantly aided the spread of the disease. And others have argued that the course of the war (and subsequent peace treaty) was influenced by the pandemic." Kahn has developed a model that can be used to test these theories.<ref>{{cite web |title=The 'Spanish' Influenza pandemic and its relation to World War I |url=http://ww1centenary.oucs.ox.ac.uk/body-and-mind/the-spanish-influenza-pandemic-and-its-relation-to-the-first-world-war/ |website=World War I Centenary |publisher=University of Oxford JISC |access-date=11 August 2020 |archive-date=5 August 2020 |archive-url=https://web.archive.org/web/20200805020700/http://ww1centenary.oucs.ox.ac.uk/body-and-mind/the-spanish-influenza-pandemic-and-its-relation-to-the-first-world-war/ |url-status=live }}</ref>

===Economic===
[[File:SpanishFluPosterAlberta.png|thumb|upright|Provincial Board of Health poster from [[Alberta, Canada]]]]
Many businesses in the entertainment and service industries suffered losses in revenue, while the healthcare industry reported profit gains.{{sfn|Garret|2007}} Historian Nancy Bristow has argued that the pandemic, when combined with the increasing number of women attending college, contributed to the success of women in nursing. This was due in part to the failure of medical doctors, who were predominantly men, to contain the illness. Nursing staff, who were mainly women, celebrated the success of their patient care and did not associate the spread of the disease with their work.<ref>{{cite web | vauthors = Lindley R |title=The Forgotten American Pandemic: Historian Dr. Nancy K. Bristow on the Influenza Epidemic of 1918 |url= http://hnn.us/article/146655 |url-status=live |archive-url= https://web.archive.org/web/20140808052318/http://hnn.us/article/146655 |archive-date=8 August 2014 |access-date=4 August 2014 |website=hnn.us |date=6 June 2012 }}</ref>

A 2020 study found that U.S. cities that implemented early and extensive non-medical measures (quarantine, etc.) suffered no additional adverse economic effects due to implementing those measures.<ref>{{cite web|date=2 April 2020|title=What can the Spanish Flu teach us about the COVID-19 pandemic?|url=https://www.weforum.org/agenda/2020/04/pandemic-economy-lessons-1918-flu|website=[[World Economic Forum]]|access-date=8 April 2020|archive-date=9 April 2020|archive-url=https://web.archive.org/web/20200409101044/https://www.weforum.org/agenda/2020/04/pandemic-economy-lessons-1918-flu/|url-status=live}}
</ref><ref>{{Cite journal|vauthors=Correia S, Luck S, Verner E|s2cid=216202133|date=2020|title=Pandemics Depress the Economy, Public Health Interventions Do Not: Evidence from the 1918 Flu|url=https://www.ssrn.com/abstract=3561560|journal=SSRN Working Paper Series|doi=10.2139/ssrn.3561560|arxiv=2207.11636 |issn=1556-5068|access-date=14 April 2020|archive-date=27 July 2021|archive-url=https://web.archive.org/web/20210727045639/https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3561560|url-status=live}}
</ref> However, the validity of this study has been questioned because of the coincidence of WWI and other problems with data reliability.<ref>{{cite news |vauthors=Kemp J |title=RPT-COLUMN-Coronavirus lockdowns: can we learn from the 1918 influenza pandemic? Kemp |url=https://www.reuters.com/article/global-economy-kemp-idUSL8N2BV512 |access-date=17 August 2021 |publisher=Reuters |date=7 April 2020 |archive-date=17 August 2021 |archive-url=https://web.archive.org/web/20210817174043/https://www.reuters.com/article/global-economy-kemp-idUSL8N2BV512 |url-status=live }}</ref>

===Long-term effects===
A 2006 study in the ''Journal of Political Economy'' found that "cohorts ''in utero'' during the pandemic displayed reduced educational attainment, increased rates of physical disability, lower income, lower socioeconomic status, and higher [[transfer payments]] received compared with other birth cohorts."<ref>{{Cite journal | vauthors = Almond D |s2cid=20055129 |date=1 August 2006 |title=Is the 1918 Influenza Pandemic Over? Long-Term Effects of In Utero Influenza Exposure in the Post-1940 U.S. Population |journal=Journal of Political Economy |volume=114 |issue=4 |pages=672–712 |doi=10.1086/507154 |issn=0022-3808}}</ref> A 2018 study found that the pandemic reduced educational attainment in populations.<ref>{{cite journal | vauthors = Beach B, Ferrie JP, Saavedra MH |date=2018 |title=Fetal shock or selection? The 1918 influenza pandemic and human capital development |url= http://www.nber.org/papers/w24725|url-status=live|doi=10.3386/w24725 |archive-url= https://web.archive.org/web/20180618131115/http://www.nber.org/papers/w24725 |archive-date=18 June 2018 |access-date=18 June 2018 |doi-access=free |website=nber.org|series=Working Paper Series }}</ref> The flu has also been linked to the outbreak of [[encephalitis lethargica]] in the 1920s.{{sfn|Vilensky|Foley|Gilman|2007}}

Survivors faced an elevated mortality risk. Some survivors did not fully recover from physiological conditions resulting from infection.<ref>{{cite web | vauthors = Fottrell Q | date = 25 August 2020 | title = Another warning from the 1918 flu for COVID-19: 'Survival does not mean that individuals fully recovered' | url = https://www.marketwatch.com/story/another-warning-from-1918-spanish-flu-for-covid-19-survival-does-not-mean-that-individuals-fully-recovered-2020-08-18 | archive-url = https://web.archive.org/web/20200824075950/https://www.marketwatch.com/story/another-warning-from-1918-spanish-flu-for-covid-19-survival-does-not-mean-that-individuals-fully-recovered-2020-08-18 | archive-date = 24 August 2020 | work = MarketWatch }}</ref>

==Legacy==
[[File:1918 Influenza epidemic burial site.jpg|thumb|Mass burial site of flu victims from 1918 in [[Auckland]], New Zealand]]
The Spanish flu began to fade from public awareness over the decades until the [[Avian influenza|bird flu]] and other pandemics in the 1990s and 2000s.{{sfn|Honigsbaum|2008}}<ref name = "Beiner_2021">{{cite book | vauthors = Beiner G | veditors = Beiner G |title=Pandemic Re-Awakenings: The Forgotten and Unforgotten 'Spanish' Flu of 1918–1919 |date=2021 |publisher=Oxford University Press |isbn=9780192843739 |pages=346–376 |url=https://global.oup.com/academic/product/pandemic-re-awakenings-9780192843739 |chapter=Rediscovering the Great Flu between Pre-Forgetting and Post-Forgetting}}</ref> This has led some historians to label the Spanish flu a "forgotten pandemic".{{sfn|Crosby|2003}} However, this label has been challenged by the historian [[Guy Beiner]], who demonstrated how the pandemic was overshadowed by the commemoration of the First World War and mostly neglected in mainstream historiography, yet was remembered in private and local traditions across the globe.<ref name = "Beiner_2021" />

There are various theories of why the Spanish flu was "forgotten". The rapid pace of the pandemic, which killed most of its victims in the United States within less than nine months, resulted in limited media coverage. The general population was familiar with patterns of pandemic disease in the late 19th and early 20th centuries: typhoid, [[yellow fever]], [[diphtheria]], and cholera all occurred near the same time. These outbreaks probably lessened the significance of the influenza pandemic for the public.{{sfn|Morrisey|1986}} In some areas, the flu was not reported on, the only mention being that of advertisements for medicines claiming to cure it.{{sfn|Benedict|Braithwaite|2000|p=38}}

Additionally, the outbreak coincided with the deaths and media focus on the First World War.{{sfn|Crosby|2003|pp=320–322}} The majority of fatalities, from both the war and the epidemic, were among young adults. The high number of war-related deaths of young adults may have overshadowed the deaths caused by flu.{{sfn|Simonsen|Clarke|Schonberger|Arden|1998}} Particularly in Europe, where the war's toll was high, the flu may not have had a tremendous psychological impact or may have seemed an extension of the war's tragedies.{{sfn|Simonsen|Clarke|Schonberger|Arden|1998}}

===In literature and other media===
[[File:"Stuffy Cars Breed Disease" - Better Ventilation.png|thumb|US comic published in 1922]]
Despite the toll of the pandemic, it was never a large theme in American literature.<ref name=":0" /> Alfred Crosby suspects it was overshadowed by World War I.{{sfn|Crosby|2003|p=315}} [[Katherine Anne Porter]]'s 1939 novella ''[[Pale Horse, Pale Rider]]'' is one of the most well-known fictional accounts of the pandemic.<ref name=":0">{{Cite web |title=Why Did So Few Novels Tackle the 1918 Pandemic? |url=https://www.smithsonianmag.com/arts-culture/flu-novels-great-pandemic-180965205/ |access-date=2023-06-06 |website=Smithsonian Magazine |language=en |archive-date=6 June 2023 |archive-url=https://web.archive.org/web/20230606064620/https://www.smithsonianmag.com/arts-culture/flu-novels-great-pandemic-180965205/ |url-status=live }}</ref> The 2006 novel ''[[The Last Town on Earth]]'' focuses on a town which attempts to limit the spread of the flu by preventing people from entering or leaving.<ref>{{Cite web | vauthors = Hansen L |date=24 September 2006 |title=Mullen's View from 'The Last Town on Earth' |url=https://www.npr.org/2006/09/24/6133594/mullens-view-from-the-last-town-on-earth |access-date=11 June 2023 |website=[[NPR]]}}</ref> ''[[The Pull of the Stars]]'' is a 2020 novel by [[Emma Donoghue]] set in Dublin during the Spanish flu. Publishers fast-tracked publication because of the then ongoing [[COVID-19 pandemic]].<ref>{{Cite web |vauthors=Corrigan M |date=20 July 2020 |title=1918 Flu Inspired Donoghue's 'Pull Of The Stars' — A Disquieting Pandemic Novel |url=https://www.npr.org/2020/07/20/892279658/1918-flu-inspired-donoghues-pull-of-the-stars-a-disquieting-pandemic-novel |access-date=6 June 2023 |website=[[NPR]] |archive-date=6 June 2023 |archive-url=https://web.archive.org/web/20230606064627/https://www.npr.org/2020/07/20/892279658/1918-flu-inspired-donoghues-pull-of-the-stars-a-disquieting-pandemic-novel |url-status=live }}</ref>

===Comparison with other pandemics===
{{Notable flu pandemics}}

==Research==
{{Main|Spanish flu research}}
[[File:Reconstructed Spanish Flu Virus.jpg|thumb|An electron micrograph showing recreated 1918 influenza virions]]
Similarities between a reconstruction of the virus and avian viruses, combined with the human pandemic preceding the first reports of influenza in swine, led researchers to conclude the influenza virus jumped directly from birds to humans, and swine caught the disease from humans.<ref name=influenzareport>{{cite book |quote=Sometimes a virus contains both avian-adapted genes and human-adapted genes. Both the [[H2N2]] and [[H3N2]] pandemic strains contained avian flu virus [[RNA]] segments. "While the pandemic human influenza viruses of 1957 (H2N2) and 1968 (H3N2) arose through reassortment between human and avian viruses, the influenza virus causing the 'Spanish flu' in 1918 appears to be entirely derived from an avian source (Belshe 2005). |chapter-url=http://www.influenzareport.com/ir/ai.htm |chapter=Chapter Two: Avian Influenza |vauthors=Harder TC, Ortrud W |title=Influenza Report 2006 |publisher=published online |access-date=26 October 2007 |archive-date=9 August 2017 |archive-url=https://web.archive.org/web/20170809185926/http://www.influenzareport.com/ir/ai.htm |url-status=live }}</ref>{{sfn|Taubenberger|Reid|Lourens|Wang|2005}} More recent research has suggested the strain may have originated in a nonhuman, mammalian species,{{sfn|Vana|Westover|2008}} in 1882–1913.{{sfn|dos Reis|Hay|Goldstein|2009}} This ancestor virus diverged about 1913–1915 into the classical swine and human H1N1 influenza lineages. The last common ancestor of human strains dates between February 1917 and April 1918. Because pigs are more readily infected with avian influenza viruses than are humans, they were suggested as the original recipients of the virus, passing the virus to humans sometime between 1913 and 1918.{{cn|date=May 2025}}

[[File:Influenza virus research.jpg|thumb|upright|Dr Terrence Tumpey examines a reconstructed version of the Spanish flu virus at the [[CDC]]]]
An effort to recreate the Spanish flu strain (a [[Strain (biology)|strain]] of influenza A subtype H1N1) was a collaboration among the [[Armed Forces Institute of Pathology]], the [[Agricultural Research Service|USDA ARS]] Southeast Poultry Research Laboratory, and [[Mount Sinai School of Medicine]] in New York City. The effort resulted in the announcement in 2005 that the group had successfully determined the virus' [[genetic sequence]], using historic tissue samples recovered by pathologist [[Johan Hultin]] from an Inuit female flu victim buried in the Alaskan [[permafrost]] and samples preserved from American soldiers.<ref>{{cite web |url=https://www.cdc.gov/media/pressrel/r051005.htm |publisher=Center for Disease Control |title=Researchers reconstruct 1918 pandemic influenza virus; effort designed to advance preparedness |access-date=2 September 2009 |archive-url=https://web.archive.org/web/20111019045108/http://www.cdc.gov/media/pressrel/r051005.htm |archive-date=19 October 2011 |url-status=live }}</ref><ref>{{cite web |title=Closing In On a Killer: Scientists Unlock Clues to the Spanish Influenz Virus |url=https://www.medicalmuseum.mil/index.cfm?p=exhibits.virtual.1918killerflu.page_01 |website=National Museum of Health and Medicine |access-date=23 March 2020 |archive-date=2 May 2020 |archive-url=https://web.archive.org/web/20200502042213/https://www.medicalmuseum.mil/index.cfm?p=exhibits.virtual.1918killerflu.page_01 |url-status=live }}</ref><ref>{{cite news |vauthors=Kolata G |title=Scientists Uncover Clues To Flu Epidemic of 1918 |url=https://www.nytimes.com/1999/02/16/us/scientists-uncover-clues-to-flu-epidemic-of-1918.html |access-date=23 March 2020 |work=The New York Times |date=16 February 1999 |archive-date=22 March 2020 |archive-url=https://web.archive.org/web/20200322015429/https://www.nytimes.com/1999/02/16/us/scientists-uncover-clues-to-flu-epidemic-of-1918.html |url-status=live }}</ref>{{sfn|Taubenberger|Reid|Lourens|Wang|2005}} This enabled researchers at the [[Centers for Disease Control and Prevention]] (CDC) and the [[Mount Sinai School of Medicine]], led by Dr Terrence Tumpey, to synthesize RNA segments from the H1N1 virus and reconstruct infective virus particles.<ref name=":02">{{Cite web |vauthors=Jordan D, Tumpey T, Jester B |title=The Deadliest Flu: The Complete Story of the Discovery and Reconstruction of the 1918 Pandemic Virus |url=https://archive.cdc.gov/#/details?url=https://www.cdc.gov/flu/pandemic-resources/reconstruction-1918-virus.html |access-date=2024-06-22 |website=archive.cdc.gov |archive-date=15 July 2020 |archive-url=https://web.archive.org/web/20200715061619/https://www.cdc.gov/media/releases/2019/s0424-highest-measles-cases-since-elimination.html#/details?url=https://www.cdc.gov/flu/pandemic-resources/reconstruction-1918-virus.html |url-status=live }}</ref> These were subsequently used to experimentally infect mice, ferrets, and macaques, providing information about how to prevent and control future pandemics.<ref>{{cite journal | vauthors = Taubenberger JK, Baltimore D, Doherty PC, Markel H, Morens DM, Webster RG, Wilson IA | title = Reconstruction of the 1918 influenza virus: unexpected rewards from the past | journal = mBio | volume = 3 | issue = 5 | date = November 2012 | pmid = 22967978 | pmc = 3448162 | doi = 10.1128/mBio.00201-12 }}</ref>

In 2007, Kobasa et al. reported that monkeys (''[[Macaca fascicularis]]'') infected with the recreated flu strain exhibited classic symptoms of the 1918 pandemic, and died from an overreaction of the immune system.{{sfn|Kobasa|et al.|2007}} This may explain why the Spanish flu had its surprising effect on younger, healthier people, as a person with a stronger immune system would potentially have a stronger overreaction.<ref>{{cite news |url=https://www.usatoday.com/tech/science/discoveries/flu-research.htm?POE=NEWISVA |newspaper=USA Today |title=Research on monkeys finds resurrected 1918 flu killed by turning the body against itself |access-date=14 August 2008 |archive-url=https://web.archive.org/web/20090305113915/http://www.usatoday.com/tech/science/discoveries/flu-research.htm?POE=NEWISVA |archive-date=5 March 2009 |url-status=live }}</ref>

In December 2008, research by [[Yoshihiro Kawaoka]] of the [[University of Wisconsin]] linked three specific genes (termed PA, PB1, and PB2) and a [[nucleoprotein]] derived from Spanish flu samples to the ability of the 1918 flu virus to invade the lungs and cause pneumonia. These genes were inserted into a modern H1N1 strain and triggered similar symptoms in animal testing.{{sfn|Fox|2008}}

In 2008 an investigation used the virus sequence to obtain the [[Hemagglutinin (influenza)|Hemagglutinin (HA)]] antigen and observe the adaptive immunity in 32 survivors of the 1918 pandemic; all of them presented seroreactivity and 7 of 8 further tested presented [[memory B cell]]s able to produce antibodies that bound to the HA antigen, highlighting the ability of [[immunological memory]].<ref>{{cite journal |vauthors=Yu X, Tsibane T, McGraw PA, House FS, Keefer CJ, Hicar MD, Tumpey TM, Pappas C, Perrone LA, Martinez O, Stevens J, Wilson IA, Aguilar PV, Altschuler EL, Basler CF, Crowe JE |date=September 2008 |title=Neutralizing antibodies derived from the B cells of 1918 influenza pandemic survivors |journal=Nature |volume=455 |issue=7212 |pages=532–536 |bibcode=2008Natur.455..532Y |doi=10.1038/nature07231 |pmc=2848880 |pmid=18716625}}</ref>{{sfn|Taubenberger|Reid|Lourens|Wang|2005}}

In June 2010, a team at the Mount Sinai School of Medicine reported the [[2009 flu pandemic vaccine]] provided some cross-protection against the Spanish flu pandemic strain.{{sfn|Fox|2010}}

In 2013, the AIR Worldwide Research and Modeling Group "estimated the effects of a similar pandemic occurring today using the AIR Pandemic Flu Model". In the model, "a modern-day 'Spanish flu' event would result in additional life insurance losses of between US$15.3–27.8&nbsp;billion in the United States alone", with 188,000–337,000&nbsp;deaths in the United States.{{sfn|Madhav|2013}}

In 2018, Michael Worobey, a professor at the [[University of Arizona]] who is examining the history of the 1918 pandemic, revealed that he obtained tissue slides created by William Rolland, a physician who reported on a respiratory illness likely to be the virus while a pathologist in the British military during World War One.<ref>{{cite news | vauthors = Branswell H |url=https://www.statnews.com/2018/12/05/1918-spanish-flu-unraveling-mystery |title=A shot-in-the-dark e-mail leads to a century-old family treasure&nbsp;– and hope of cracking a deadly flu's secret |magazine=Stat |date=5 December 2018 |access-date=5 December 2018 |archive-url=https://web.archive.org/web/20181205172533/https://www.statnews.com/2018/12/05/1918-spanish-flu-unraveling-mystery/ |archive-date=5 December 2018 |url-status=live }}</ref><ref>{{cite journal |vauthors=Hammond JA, Rolland W, Shore TH |title=Purulent bronchitis: A study of cases occurring amongst the British troops at a base in France |journal=The Lancet |date=14 July 1917 |volume=190 |issue=4898 |pages=41–45 |doi=10.1016/S0140-6736(01)56229-7 | url = https://www.statnews.com/wp-content/uploads/2018/12/Hammond.1917.purulent.bronchitis.pdf | archive-url=https://web.archive.org/web/20190826134026/https://www.statnews.com/wp-content/uploads/2018/12/Hammond.1917.purulent.bronchitis.pdf | archive-date=26 August 2019 }}</ref><ref>{{cite web |url=http://ww1centenary.oucs.ox.ac.uk/body-and-mind/the-influenza-pandemic-of-1918/ |title=The Influenza Pandemic of 1918 |website=World War 1 Centenary |publisher=University of Oxford |place=Oxford, England |access-date=8 December 2018 |archive-url=https://web.archive.org/web/20181209125259/http://ww1centenary.oucs.ox.ac.uk/body-and-mind/the-influenza-pandemic-of-1918/ |archive-date=9 December 2018 |url-status=live }}</ref> Worobey extracted tissue from the slides to potentially reveal more about the origin of the pathogen.<ref name=Cox>{{cite journal | vauthors = Cox J, Gill D, Cox F, Worobey M | title = Purulent bronchitis in 1917 and pandemic influenza in 1918 | journal = The Lancet. Infectious Diseases | volume = 19 | issue = 4 | pages = 360–361 | date = April 2019 | pmid = 30938298 | doi = 10.1016/s1473-3099(19)30114-8 | s2cid = 91189842 | doi-access = free }}</ref>

== See also ==
{{Portal|Medicine|Viruses}}
* {{Annotated link |1918 flu pandemic in India}}
* {{Annotated link |2009 swine flu pandemic}}
* {{Annotated link |Anti-Mask League of San Francisco}}
* {{Annotated link |COVID-19 pandemic}}
* {{Annotated link |Pandemic}}
* [[List of epidemics and pandemics]]
* [[List of Spanish flu cases]]

==Footnotes==
{{notelist}}

== References ==
===Citations===
{{reflist}}

===Bibliography===
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* {{cite journal | vauthors = Johnson NP, Mueller J | title = Updating the accounts: global mortality of the 1918–1920 "Spanish" influenza pandemic | journal = Bulletin of the History of Medicine | volume = 76 | issue = 1 | pages = 105–115 | date = 2002 | pmid = 11875246 | doi = 10.1353/bhm.2002.0022 | s2cid = 22974230 }}
* {{cite book | veditors = Knobler S, Mack A, Mahmoud A, Lemon S | title = The Threat of Pandemic Influenza: Are We Ready? Workshop Summary (2005) | chapter = 1: The Story of Influenza | chapter-url = https://www.ncbi.nlm.nih.gov/books/NBK22148/ | publisher = The National Academies Press | place = Washington, DC | pages = 60–61 | ref = {{harvid|Knobler|2005}} | year = 2005 | access-date = 20 August 2019 | archive-date = 23 December 2020 | archive-url = https://web.archive.org/web/20201223130139/https://www.ncbi.nlm.nih.gov/books/NBK22148/ | url-status = live }}
* {{cite journal | vauthors = Kobasa D, Jones SM, Shinya K, Kash JC, Copps J, Ebihara H, Hatta Y, Kim JH, Halfmann P, Hatta M, Feldmann F, Alimonti JB, Fernando L, Li Y, Katze MG, Feldmann H, Kawaoka Y | title = Aberrant innate immune response in lethal infection of macaques with the 1918 influenza virus | journal = Nature | volume = 445 | issue = 7125 | pages = 319–323 | date = January 2007 | pmid = 17230189 | doi = 10.1038/nature05495 | ref = {{harvid|Kobasa|et al.|2007}} | s2cid = 4431644 | doi-access = free | bibcode = 2007Natur.445..319K }}
* {{cite book | vauthors = Kohn GC | title = Encyclopedia of plague and pestilence: from ancient times to the present | via = Google Books | url = https://books.google.com/books?id=tzRwRmb09rgC&pg=PA363 | publisher = Infobase Publishing | year = 2007 | page = 363 | edition = 3rd | isbn = 978-0-8160-6935-4 | access-date = 29 October 2015 | archive-date = 1 January 2016 | archive-url = https://web.archive.org/web/20160101182730/https://books.google.com/books?id=tzRwRmb09rgC&pg=PA363 | url-status = live }}
* {{cite web | vauthors = Madhav N | title = Modeling a Modern Day Spanish Flu Pandemic | url = https://www.air-worldwide.com/SiteAssets/Publications/AIR-Currents/2013/Attachments/Modeling-a-Modern-Day-Spanish-Flu-Pandemic | date = February 2013 | publisher = [[AIR Worldwide]] | format = PDF | access-date = 5 May 2020 | archive-date = 26 February 2020 | archive-url = https://web.archive.org/web/20200226185550/https://www.air-worldwide.com/SiteAssets/Publications/AIR-Currents/2013/Attachments/Modeling-a-Modern-Day-Spanish-Flu-Pandemic | url-status = live }}
* {{cite journal | vauthors = More AF, Loveluck CP, Clifford H, Handley MJ, Korotkikh EV, Kurbatov AV, McCormick M, Mayewski PA | title = The Impact of a Six-Year Climate Anomaly on the "Spanish Flu" Pandemic and WWI | journal = GeoHealth | volume = 4 | issue = 9 | pages = e2020GH000277 | date = September 2020 | pmid = 33005839 | pmc = 7513628 | doi = 10.1029/2020GH000277 | bibcode = 2020GHeal...4..277M | doi-access = free | issn=2471-1403 }}
* {{cite journal | vauthors = Morrisey CR | title = The Influenza Epidemic of 1918 | journal = Navy Medicine | volume = 77 | issue = 3 | year = 1986 | pages = 11–17 | url = https://archive.org/details/U.s.NavyMedicineVol.77No.3May-june1986 }}
* {{cite journal | vauthors = Noymer A, Carreon D, Johnson N | title = Questioning the salicylates and influenza pandemic mortality hypothesis in 1918–1919 | journal = Clinical Infectious Diseases | volume = 50 | issue = 8 | pages = 1203; author reply 1203 | date = April 2010 | pmid = 20233050 | doi = 10.1086/651472 | doi-access = free }}
* {{cite book | vauthors = Pankhurst R | title = An Introduction to the Medical History of Ethiopia | place = Trenton | publisher = Red Sea Press | year = 1991 | isbn = 978-0-932415-45-5 }}
* {{cite journal | vauthors = Patterson KD, Pyle GF | title = The geography and mortality of the 1918 influenza pandemic | journal = Bulletin of the History of Medicine | volume = 65 | issue = 1 | pages = 4–21 | date = 1991 | pmid = 2021692 }}
* {{cite encyclopedia
 | veditors       = Porras-Gallo M, Davis RA
 |title           = The Spanish Influenza Pandemic of 1918–1919: Perspectives from the Iberian Peninsula and the Americas
 |publisher       = University of Rochester Press
 |year            = 2014
 |isbn            = 978-1-58046-496-3
 |volume          = 30
 |encyclopedia    = Rochester Studies in Medical History
 |url             = https://books.google.com/books?id=-j53BQAAQBAJ&q=spanish+flu+davis&pg=PA51
 |via             = Google Books
 |access-date     = 9 November 2020
|archive-date    = 22 January 2021
|archive-url     = https://web.archive.org/web/20210122003928/https://books.google.com/books?id=-j53BQAAQBAJ&q=spanish+flu+davis&pg=PA51
 |url-status      = live
}}
* {{cite book | vauthors = Price-Smith AT | title = Contagion and Chaos | place = Cambridge, MA | publisher = MIT Press | year = 2008 | isbn = 978-0-262-66203-1 }}
* {{cite book | vauthors = Qureshi AI |title=Ebola Virus Disease: From Origin to Outbreak |url=https://books.google.com/books?id=7zyXCgAAQBAJ&q=Ebola+Virus+Disease:+From+Origin+to+Outbreak+Adnan+1918+pandemic&pg=PA42 |via=Google Books |publisher=Academic Press |year=2016 |isbn=978-0-12-804242-7 }}
* {{cite book | vauthors = Rice GW | title = Black November; the 1918 Influenza Pandemic in New Zealand | publisher = University of Canterbury Press | year = 2005 | isbn = 978-1-877257-35-3 | edition = 2nd | author-link = Geoffrey Rice }}
* {{cite journal | vauthors = Simonsen L, Clarke MJ, Schonberger LB, Arden NH, Cox NJ, Fukuda K | title = Pandemic versus epidemic influenza mortality: a pattern of changing age distribution | journal = The Journal of Infectious Diseases | volume = 178 | issue = 1 | pages = 53–60 | date = July 1998 | pmid = 9652423 | doi = 10.1086/515616 | citeseerx = 10.1.1.327.2581 | jstor = 30114117 }}
* {{cite book  | vauthors = Spinney L | title=Pale rider: the Spanish flu of 1918 and how it changed the world |date=2018 |publisher=Vintage |isbn=978-1-78470-240-3 |place=London |oclc=1090305029}}
* {{cite journal | vauthors = Starko KM | title = Salicylates and pandemic influenza mortality, 1918–1919 pharmacology, pathology, and historic evidence | journal = Clinical Infectious Diseases | volume = 49 | issue = 9 | pages = 1405–1410 | date = November 2009 | pmid = 19788357 | doi = 10.1086/606060 | doi-access = free }} {{lay source | author = [[Infectious Diseases Society of America]] |template=cite news |url=https://www.sciencedaily.com/releases/2009/10/091002132346.htm |title=Aspirin Misuse May Have Made 1918 Flu Pandemic Worse |date= 3 October 2009 |work=[[ScienceDaily]]|archive-url=https://web.archive.org/web/20210109085900/https://www.sciencedaily.com/releases/2009/10/091002132346.htm |archive-date=9 January 2021 }}
* {{cite journal | vauthors = Zhuang W, Liu J, Li W | title = hsa-miR-33-5p as a Therapeutic Target Promotes Apoptosis of Breast Cancer Cells ''via'' Selenoprotein T | journal = Frontiers in Medicine | volume = 50 | issue = 8 | pages = 651473 | year = 2010 | pmid = 33987194 | doi = 10.1086/651473 | doi-access = free | pmc = 8110722 }}
* {{cite journal | vauthors = Taubenberger JK, Reid AH, Janczewski TA, Fanning TG | title = Integrating historical, clinical and molecular genetic data in order to explain the origin and virulence of the 1918 Spanish influenza virus | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 356 | issue = 1416 | pages = 1829–1839 | date = December 2001 | pmid = 11779381 | pmc = 1088558 | doi = 10.1098/rstb.2001.1020 }}
* {{cite journal | vauthors = Taubenberger JK, Reid AH, Lourens RM, Wang R, Jin G, Fanning TG | title = Characterization of the 1918 influenza virus polymerase genes | journal = Nature | volume = 437 | issue = 7060 | pages = 889–893 | date = October 2005 | pmid = 16208372 | doi = 10.1038/nature04230 | s2cid = 4405787 | doi-access = free | bibcode = 2005Natur.437..889T }}
* {{cite journal | vauthors = Taubenberger JK, Morens DM | title = 1918 Influenza: the mother of all pandemics | journal = Emerging Infectious Diseases | volume = 12 | issue = 1 | pages = 15–22 | date = January 2006 | pmid = 16494711 | pmc = 3291398 | doi = 10.3201/eid1201.050979 }}
* {{cite journal | vauthors = Vana G, Westover KM | title = Origin of the 1918 Spanish influenza virus: a comparative genomic analysis | journal = Molecular Phylogenetics and Evolution | volume = 47 | issue = 3 | pages = 1100–1110 | date = June 2008 | pmid = 18353690 | doi = 10.1016/j.ympev.2008.02.003 | bibcode = 2008MolPE..47.1100V }}
* {{cite journal | vauthors = Vilensky JA, Foley P, Gilman S | title = Children and encephalitis lethargica: a historical review | journal = Pediatric Neurology | volume = 37 | issue = 2 | pages = 79–84 | date = August 2007 | pmid = 17675021 | doi = 10.1016/j.pediatrneurol.2007.04.012 | url = http://www.pedneur.com/article/S0887-8994(07)00194-4/abstract | access-date = 22 November 2016 | url-status = live | archive-url = https://web.archive.org/web/20200417064629/https://www.pedneur.com/article/S0887-8994(07)00194-4/abstract | archive-date = 17 April 2020 | url-access = subscription }}
{{refend}}

== Further reading ==
<!-- {{no more links|'''Note''': 27 links and 4 videos are more than enough|date=October 2024 --  ~~~~}} -->
{{refbegin|30em}}
* {{cite journal |vauthors=Beiner G |author-link1=Guy Beiner |title=Out in the Cold and Back: New-Found Interest in the Great Flu |journal=Cultural and Social History |date=2006 |volume=3 |issue=4 |pages=496–505 |doi=10.1191/1478003806cs070ra |doi-broken-date=1 November 2024 |url=https://www.tandfonline.com/doi/abs/10.1191/1478003806cs070ra |access-date=29 May 2020 |archive-date=24 July 2020 |archive-url=https://web.archive.org/web/20200724110257/https://www.tandfonline.com/doi/abs/10.1191/1478003806cs070ra |url-status=live }}
* {{Citation|title=Pandemic Re-Awakenings: The Forgotten and Unforgotten 'Spanish' Flu of 1918–1919|url=https://global.oup.com/academic/product/pandemic-re-awakenings-9780192843739|year=2022|publication-place=Oxford and New York|publisher=Oxford University Press|isbn=9780192843739|veditors=Beiner G}}
* {{cite book | vauthors = Brown J |title=Influenza: The Hundred Year Hunt to Cure the Deadliest Disease in History |publisher=Atria |place=New York |year=2018 |isbn=978-1-5011-8124-5}}
* {{cite journal | last=Byerly | first=Carol R. | title=The U.S. military and the influenza pandemic of 1918–1919 | journal=Public Health Reports (Washington, D.C.: 1974) | volume=125 Suppl 3 | issue=Suppl 3 | date=2010 | issn=0033-3549 | pmid=20568570 | pmc=2862337 | pages=82–91}}
* {{cite book | vauthors = Byerly CR |title=Fever of War: The Influenza Epidemic in the U.S. Army during World War I |publisher=New York University Press |place=New York|year=2005|isbn=0814799248}}
* {{cite journal | vauthors = Chandra S, Christensen J, Likhtman S | title = Connectivity and seasonality: the 1918 influenza and COVID-19 pandemics in global perspective. | journal = Journal of Global History | date = November 2020 | volume = 15 | issue = 3 | pages = 408–20 | doi = 10.1017/S1740022820000261 | s2cid = 228988279 | doi-access = free }}
* {{cite journal |last1=Cimino |first1=Eric |title=The Supervisors are Carrying the Bag: The Nurses' Emergency Council, Settlement Houses, and the 1918 Influenza Pandemic in New York City |journal=New York History |date=Winter 2023–2024 |volume=104 |issue=2 |pages=296–314 |doi=10.1353/nyh.2023.a918265 |url=https://www.academia.edu/116044936 |archive-date=19 January 2025 |access-date=16 November 2024 |archive-url=https://web.archive.org/web/20250119193827/https://www.academia.edu/116044936 |url-status=live }}
* {{cite book | vauthors = Collier R |title=The Plague of the Spanish Lady – The Influenza Pandemic of 1918–19 |publisher=Atheneum |year=1974 |isbn=978-0-689-10592-0}}
* {{cite book |title=More Deadly Than War: The Hidden History of the Spanish Flu and the First World War | vauthors = Davis KC |publisher=Henry Holt and Co. |year=2018 |isbn=978-1250145123 }}
* {{cite web |vauthors = Dorratoltaj N |url = https://www.air-worldwide.com/Publications/AIR-Currents/2018/What-the-1918-Flu-Pandemic-Can-Teach-Today-s-Insurers/ |title = What the 1918 Flu Pandemic Can Teach Today's Insurers |publisher = AIR Research and Modeling Group |date = 29 March 2018 |access-date = 28 May 2019 |veditors = Carrell H |archive-date = 7 November 2020 |archive-url = https://web.archive.org/web/20201107223412/https://www.air-worldwide.com/Publications/AIR-Currents/2018/What-the-1918-Flu-Pandemic-Can-Teach-Today-s-Insurers/ |url-status = live }}
* {{cite book | vauthors=Duncan K | year=2003 | title=Hunting the 1918 flu: one scientist's search for a killer virus | publisher=University of Toronto Press | isbn=978-0-8020-8748-5 | url=https://books.google.com/books?id=HPDI_30wRsEC | access-date=3 May 2020 | archive-date=24 July 2020 | archive-url=https://web.archive.org/web/20200724112134/https://books.google.com/books?id=HPDI_30wRsEC | url-status=live }}
* {{cite book | vauthors = Humphries MO |title=The Last Plague: Spanish Influenza and the Politics of Public Health in Canada |year=2013 |publisher=University of Toronto Press |isbn=978-1-4426-1044-6 }}
* {{cite book | vauthors = Johnson N |title=Britain and the 1918–19 Influenza Pandemic: A Dark Epilogue |publisher=Routledge |place=London and New York|year=2006|isbn=978-0-415-36560-4}}
* {{cite journal|vauthors=Johnson N|year=2003|title=Measuring a pandemic: Mortality, demography and geography|url=https://popolazioneestoria.it/article/view/174|journal=Popolazione e Storia|volume=4|issue=2|pages=31–52|archive-date=25 December 2022|access-date=29 July 2021|archive-url=https://web.archive.org/web/20221225120310/https://popolazioneestoria.it/article/view/174|url-status=live}}
* {{cite journal | vauthors = Johnson N |year=2003|title=Scottish 'flu&nbsp;– The Scottish mortality experience of the 'Spanish flu'|journal=Scottish Historical Review|volume=83|issue=2|pages=216–26|doi=10.3366/shr.2004.83.2.216}}
* {{cite book|vauthors=Kolata G|author-link=Gina Kolata|title=Flu: The Story of the Great Influenza Pandemic of 1918 and the Search for the Virus That Caused It|publisher=Farrar, Straus and Giroux|place=New York|year=1999|isbn=978-0-374-15706-7|url=https://archive.org/details/isbn_9780965043267}}
* {{cite book| vauthors = Little J |author-link=Jean Little|title=If I Die Before I Wake: The Flu Epidemic Diary of Fiona Macgregor, Toronto, Ontario, 1918|publisher=Scholastic Canada|place=Markham, ON |year=2007|isbn=978-0-439-98837-7|series=[[Dear Canada]]}}
* {{cite journal | vauthors = Noymer A, Garenne M | title = The 1918 influenza epidemic's effects on sex differentials in mortality in the United States | journal = Population and Development Review | volume = 26 | issue = 3 | pages = 565–581 | year = 2000 | pmid = 19530360 | pmc = 2740912 | doi = 10.1111/j.1728-4457.2000.00565.x }}
* {{cite journal | vauthors = Oxford JS, Sefton A, Jackson R, Innes W, Daniels RS, Johnson NP | title = World War I may have allowed the emergence of "Spanish" influenza | journal = The Lancet. Infectious Diseases | volume = 2 | issue = 2 | pages = 111–114 | date = February 2002 | pmid = 11901642 | doi = 10.1016/S1473-3099(02)00185-8 }}
* {{cite journal | vauthors = Oxford JS, Sefton A, Jackson R, Johnson NP, Daniels RS | title = Who's that lady? | journal = Nature Medicine | volume = 5 | issue = 12 | pages = 1351–1352 | date = December 1999 | pmid = 10581070 | doi = 10.1038/70913 | s2cid = 5065916 | doi-access = free }}
* {{cite book |vauthors=Pettit D, Janice B |title=A Cruel Wind: Pandemic Flu in America, 1918–1920 |publisher=Timberlane Books |place=Murfreesboro, TN |year=2008 |isbn=978-0-9715428-2-2 |url-access=registration |url=https://archive.org/details/cruelwindpandemi0000pett }}
* {{cite journal | vauthors = Philips H | title = The re-appearing shadow of 1918: trends in the historiography of the 1918–19 influenza pandemic | journal = Canadian Bulletin of Medical History  | volume = 21 | issue = 1 | pages = 121–134 | year = 2010 | pmid = 15202430 | doi = 10.3138/cbmh.21.1.121 | doi-access = free }}
* {{cite journal | vauthors = Phillips H |title=The Recent Wave of 'Spanish' Flu Historiography |journal=Social History of Medicine |date=1 September 2014 |volume=27 |issue=4 |pages=789–808 |doi=10.1093/shm/hku066 }}
* {{cite book | veditors = Phillips H, Killingray D |title=The Spanish Flu Pandemic of 1918: New Perspectives |publisher=Routledge |place=London and New York |year=2003}}
* {{cite journal | vauthors = Phillips H | title = '17,'18,'19: religion and science in three pandemics, 1817, 1918, and 2019. | journal = Journal of Global History | date = November 2020 | volume = 15 | issue = 3 | pages = 434–43 | doi = 10.1017/S1740022820000315 | s2cid = 228999483 | doi-access = free }}
* {{cite journal | vauthors = Potter CW | title = A history of influenza | journal = Journal of Applied Microbiology | volume = 91 | issue = 4 | pages = 572–579 | date = October 2001 | pmid = 11576290 | doi = 10.1046/j.1365-2672.2001.01492.x | s2cid = 26392163 | doi-access = free }}
* {{cite journal | vauthors = Birge JR, Kärtner FX | title = Efficient optimization of multilayer coatings for ultrafast optics using analytic gradients of dispersion | journal = Applied Optics | volume = 46 | issue = 14 | pages = 2656–2662 | date = May 2007 | pmid = 17446914 | doi = 10.2307/132645 | jstor = 132645 }}
* {{cite journal |jstor=40267904 |url=https://www.researchgate.net/publication/236745238 |title=The Diffusion of the Influenza Pandemic of 1918 in Hartford, Connecticut |journal=Social Science History |date=2006 |volume=30 |issue=2 |pages=167–196 |doi=10.1017/S0145553200013432 |vauthors=Tuckel P, Sassler S, Maisel R, Leykam A }}
* {{cite journal | vauthors = Tumpey TM, García-Sastre A, Mikulasova A, Taubenberger JK, Swayne DE, Palese P, Basler CF | title = Existing antivirals are effective against influenza viruses with genes from the 1918 pandemic virus | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 99 | issue = 21 | pages = 13849–13854 | date = October 2002 | pmid = 12368467 | pmc = 129786 | doi = 10.1073/pnas.212519699 | author-link2 = Adolfo García-Sastre | doi-access = free | bibcode = 2002PNAS...9913849T }}
{{refend}}

===Videos===
* [https://www.youtube.com/watch?v=Rfbk1Sg8JlE We Heard the Bells: The Influenza of 1918] – [[National Institutes of Health|NIH]] interviews with Spanish Flu survivors.
* [https://www.c-span.org/video/?465724-7/influenza-pandemic-world-war Presentation by Nancy Bristow on the Influenza Pandemic and World War I, November 1, 2019], [[C-SPAN]]
* {{cite web|url=https://www.youtube.com/watch?v=3x1aLAw_xkY| archive-url=https://ghostarchive.org/varchive/youtube/20211027/3x1aLAw_xkY| archive-date=27 October 2021|title=Spanish Flu: a warning from history|publisher=[[Cambridge University]]|date=30 November 2018}}
* [https://www.youtube.com/watch?v=84nq2KxZMBw ''Dr. Wise on Influenza''] (1919){{sndash}}An 18-minute, dramatised [[public information film]] ([[silent film|silent]]) produced by Britain's [[Local Government Board]], the predecessor of the [[Department of Health and Social Care|Ministry of Health]]. Via the [[BFI National Archive|British Film Institute National Archive]].
{{cbignore}}

== External links ==
{{Scholia}}
{{Commons category}}
{{Wikiquote}}
* [http://www.influenzaarchive.org/ The American Influenza Epidemic of 1918–1919: A Digital Encyclopedia] – largest digital collection of newspapers, archival manuscripts, and interpretive essays exploring the impact of the epidemic on 50&nbsp;U.S. cities ([[University of Michigan]]).

{{Influenza}}
{{World War I}}
{{History of infectious disease}}
{{Epidemics}}
{{Authority control}}
{{portal bar|Biology|Medicine|Viruses}}

[[Category:Spanish flu pandemic| ]]
[[Category:Pandemics]]
[[Category:1910s epidemics]]
[[Category:1920s epidemics]]
[[Category:1918 disease outbreaks]]
[[Category:1919 disease outbreaks]]
[[Category:1920 disease outbreaks]]