Influenza.
D002031:Bulgaria / Q000453:epidemiology; D003604:Czechoslovakia / Q000453:epidemiology; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology*; D009426:Netherlands / Q000453:epidemiology; D009664:Norway / Q000453:epidemiology; D013557:Switzerland / Q000453:epidemiology; D013785:Thailand / Q000453:epidemiology