Vaccine effectiveness for laboratory-confirmed influenza in children 6–59 months of age, 2005–2007

To estimate the effectiveness of influenza vaccine against medical care visits for laboratory-confirmed influenza in young children we conducted a matched case–control study in children with acute respiratory illness or fever from 2005–2007. Influenza vaccine effectiveness (VE) was calculated using cases with laboratory-confirmed influenza and controls who tested negative for influenza. The effectiveness of influenza vaccine in fully vaccinated children 6–59 months of age was 56% (95% CI: 25%–74%); a significant VE was not found for partial vaccination.