Update: influenza activity--United States.
D000328:Adult; D000368:Aged; D002648:Child; D004196:Disease Outbreaks / Q000453:epidemiology; D006801:Humans; D009980:Influenza A virus; D009981:Influenza B virus; D007251:Influenza, Human / Q000453:epidemiology*; D014481:United States