Pandemic and seasonal vaccine coverage and effectiveness during the 2009–2010 pandemic influenza in an Italian adult population

Abstract

To evaluate the response to pandemic vaccination and seasonal and pandemic vaccine effectiveness (VE) in an Italian adult population, during the 2009-2010 influenza season. Data were recorded by interviewing 19,275 subjects (≥35 years), randomly recruited from the general population of the Moli-sani project. Events [influenza-like illness (ILI), hospitalization and death], which had occurred between 1 November 2009 and 31 January 2010 were considered. VE was analyzed by multivariable Poisson regression analysis. Pandemic vaccine coverage was very low (2.4%) in subjects at high-flu risk, aged 35-65 years (N = 8,048); there was no significant preventive effect of vaccine against ILI. Seasonal vaccine coverage was 26.6% in the whole population (63% in elderly and 21.9% in middle-aged subjects at high-flu risk). There was a higher risk to develop ILI in middle-age [VE: -17% (95% CI: -35,-1)] or at high flu-risk [VE: -17% (95% CI: -39, 2)] vaccinated groups. Coverage of pandemic vaccine was very low in a Southern Italy population, with no protective effect against ILI.