Influenza A virus subtype H2N2

{{for|the 1977–1978 Russian flu|1977 Russian flu}}

Some believe that the 1889–1890 Russian flu was caused by the influenzavirus A virus subtype H2N2, but the evidence is not conclusive. It is the earliest flu pandemic for which detailed records are available.{{cite web|title=Encarta on influenza|url=http://encarta.msn.com/encyclopedia_761557270_2/influenza.html|archive-url=https://web.archive.org/web/20091029210106/http://encarta.msn.com/encyclopedia_761557270_2/Influenza.html|archive-date=2009-10-29|url-status=dead|access-date=2008-08-20}} More recently, there are speculations that it might have been caused by one of the coronaviruses first discovered in the 1960s.Anthony King: [https://www.newscientist.com/article/mg24632800-700-what-four-coronaviruses-from-history-can-tell-us-about-covid-19/ What four coronaviruses from history can tell us about covid-19], on: New Scientist, 29 April 2020

{{main|1957–1958 influenza pandemic}}

The "Asian Flu" was a category 2 flu pandemic outbreak of influenzavirus A that first appeared in Guizhou, China in early 1957 and lasted until 1958.{{cite journal|last1=Pennington|first1=T H|date=2006|title=A slippery disease: a microbiologist's view|journal=BMJ|volume=332|issue=7544|pages=789–790|doi=10.1136/bmj.332.7544.789|pmc=1420718|pmid=16575087}} The first cases were reported in Singapore in February 1957. In February 1957, a new influenza A (H2N2) virus emerged in East Asia, triggering a pandemic (“Asian Flu”). This H2N2 virus was composed of three different genes from an H2N2 virus that originated from an avian influenza A virus, including the H2 hemagglutinin and the N2 neuraminidase genes. It was first reported in Singapore in February 1957, Hong Kong in April 1957, and in coastal cities in the United States in summer 1957. Some authors believe it originated from mutation in wild ducks combining with a pre-existing human strain.{{Cite book|last=Green|first=Jeffrey|title=The Bird Flu Pandemic|publisher=St. Martin's Griffin|year=2006|isbn=0312360568|url-access=registration|url=https://archive.org/details/birdflupandemicc00gree}} Other authors are less certain.{{Cite journal|last=Belshe|first=Robert B.|date=2005-11-24|title=The Origins of Pandemic Influenza — Lessons from the 1918 Virus|journal=New England Journal of Medicine|language=en|volume=353|issue=21|pages=2209–2211|doi=10.1056/NEJMp058281|pmid=16306515|issn=0028-4793|doi-access=free}} It reached Hong Kong by April, and US by June. Estimates of US and worldwide deaths caused by this pandemic varies widely depending on source; ranging from approximately 69,800 to 116,000 in the United States,{{cite web |title=1957-1958 Pandemic (H2N2 virus) |url=https://www.cdc.gov/flu/pandemic-resources/1957-1958-pandemic.html |website=Centers for Disease Control and Prevention|date=22 January 2019 |publisher=U.S. Department of Health & Human Services |access-date=4 April 2020}} and worldwide from 1 million to 4 million, with the World Health Organization (WHO) settling on "about 2 million," with an overall mortality rate of 0.6%.{{cite web |last1=Lovelace Jr. |first1=Berkeley |title=The coronavirus may be deadlier than the 1918 flu: Here's how it stacks up to other pandemics |url=https://www.cnbc.com/2020/03/26/coronavirus-may-be-deadlier-than-1918-flu-heres-how-it-stacks-up-to-other-pandemics.html |website=CNBC |date=26 March 2020 |publisher=f NBCUniversal |access-date=25 April 2020}} Asian Flu was of the H2N2 subtype (a notation that refers to the configuration of the hemagglutinin and neuraminidase proteins in the virus) of type A influenza, and an influenza vaccine was developed in 1957 to contain its outbreak.{{citation needed|date=July 2022}}

The Asian Flu strain later evolved via antigenic shift into H3N2 which caused a milder pandemic from 1968 to 1969.{{Cite book|last=Starling|first=Arthur E.|title=Plague, SARS, and the story of medicine in Hong Kong|date=2006|publisher=Hong Kong University Press|isbn=978-962-209-805-3|location=Hong Kong|oclc=68909495}}

Both the H2N2 and H3N2 pandemic strains contained avian influenza virus RNA segments.[http://www.influenzareport.com/ir/ai.htm Chapter Two : Avian Influenza by Timm C. Harder and Ortrud Werner] {{Webarchive|url=https://web.archive.org/web/20170809185926/http://www.influenzareport.com/ir/ai.htm |date=2017-08-09 }} from free on-line Book called Influenza Report 2006 which is a medical textbook that provides a comprehensive overview of epidemic and pandemic influenza.

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From October 2004 to February 2005, approximately 3,700 test kits of the 1957 H2N2 virus were accidentally spread around the world from the College of American Pathologists (CAP). CAP assists laboratories in accuracy by providing unidentified samples of viruses; private contractor Meridian Bioscience in Cincinnati, U.S., chose the 1957 strain instead of one of the less deadly avian influenza virus subtypes.{{Cite web|url=http://www.cidrap.umn.edu/news-perspective/2005/04/vendor-thought-h2n2-virus-was-safe-officials-say|title=Vendor thought H2N2 virus was safe, officials say|last=Roos|first=Robert|date=April 13, 2005|website=CIDRAP|url-status=live|archive-url=https://web.archive.org/web/20190130220010/http://www.cidrap.umn.edu/news-perspective/2005/04/vendor-thought-h2n2-virus-was-safe-officials-say|archive-date=30 January 2019|access-date=12 February 2020}} The 1957 H2N2 virus is considered deadly and the U.S. government called for the vials containing the strain to be destroyed.{{citation needed|date=July 2022}}

{{Reflist}}

• [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12458361&dopt=Citation Pandemic preparedness: lessons learnt from H2N2 and H9N2 candidate vaccines]
• {{webarchive |url=https://web.archive.org/web/20160306001251/https://www.cdc.gov/flu/h2n2bsl3.htm |title=Interim CDC-NIH Recommendation for Raising the Biosafety Level for Laboratory Work Involving Noncontemporary Human Influenza Viruses |date=6 March 2016}}
• [https://www.newscientist.com/article-topic/bird-flu/ New Scientist: Bird Flu]
• [https://www.newscientist.com/article/dn7261-pandemic-causing-asian-flu-accidentally-released/ Pandemic-causing 'Asian flu' accidentally released]
• [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6477129&dopt=Abstract Persistence of Q strain of H2N2 influenza virus in avian species: antigenic, biological and genetic analysis of avian and human H2N2 viruses]

• [https://www.fludb.org Influenza Research Database] Database of influenza sequences and related information.

{{Influenza}}

{{Epidemics}}

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{{DEFAULTSORT:Influenza A Virus Subtype H2n2}}

H2N2

Category:1957 in Hong Kong

Category:1889–1890 flu pandemic

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