Epidemiology of Influenza — The Household as the Laboratory

Little information is available about the epidemiology or virology of 2009 influenza A virus infections in community settings. Now, in a prospective study, researchers have compared the epidemiology of 2009 pandemic H1N1 influenza with that of seasonal influenza A (H1N1 and H3N2) in 99 Hong Kong households.

The researchers recruited patients presenting with acute respiratory illness at any of 14 outpatient clinics and hospital emergency departments in private hospitals across Hong Kong. Enrolled patients tested positive for influenza A virus (seasonal or pandemic) and lived with ≥2 other household members. At the first of three home visits, usually ≤24 hours after patient enrollment, all household contacts provided nasal and throat specimens…