Influenza.
D000293:Adolescent; D000328:Adult; D002648:Child; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D015994:Incidence; D009980:Influenza A virus; D009981:Influenza B virus; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male