Leads from the MMWR. Influenza--United States update on activity.
D004196:Disease Outbreaks; D006801:Humans; D009980:Influenza A virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality; D009309:National Center for Health Statistics, U.S.; D014481:United States