Influenza update.
D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D005060:Europe / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D009980:Influenza A virus; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality; D014481:United States / Q000453:epidemiology; D014852:Wales / Q000453:epidemiology