Influenza.
D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D053122:Influenza A Virus, H3N2 Subtype; D007251:Influenza, Human / Q000453:epidemiology*; D009520:New Zealand / Q000453:epidemiology; D013019:South Africa / Q000453:epidemiology