Spread of influenza.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology*; D009975:Orthomyxoviridae / Q000276:immunology; D006113:United Kingdom