title: Understanding influenza backward.
authors: Office of the Director, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 33 North Dr, Bethesda, MD 20892, USA.
authors: David M
authors: DM
authors: Morens
authors: Jeffery K
authors: JK
authors: Taubenberger
mesh_terms: D004196:Disease Outbreaks / Q000266:history / Q000706:statistics & numerical data; D005060:Europe / Q000453:epidemiology; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology* / Q000266:history* / Q000635:transmission / Q000821:virology; D012621:Seasons; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology; D047828:World War I