Pandemic alert level 6: scientific criteria for an influenza pandemic fulfilled.
D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology*; D011159:Population Surveillance; D014944:World Health Organization