title: Flu-virus prevalence comes under scrutiny.
authors: Declan
authors: D
authors: Butler
mesh_terms: D005602:France / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000821:virology*; D011159:Population Surveillance / Q000379:methods; D015995:Prevalence; D006113:United Kingdom / Q000453:epidemiology; D014744:Vietnam / Q000453:epidemiology