title: Severity of influenza.
mesh_terms: D000293:Adolescent; D002648:Child; D004196:Disease Outbreaks / Q000453:epidemiology*; D004739:England; D006801:Humans; D009980:Influenza A virus; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D012574:Schools