[Meta analysis on the effectiveness of inactivated influenza vaccine]

To understand the effectiveness of inactivated influenza vaccines (IIV).

We did a Meta analysis on IIV effectiveness with papers published during March 1998 and May 2008 in Chinese journals, using fixed model or random model according to the heterogeneity of the studies.

A total number of 13 studies were included, of which 11 were cohort studies and 2 were randomized controlled trials. Through Meta analysis on cohort studies regarding the effectiveness against influenza like illness (ILI), we noticed that the effectiveness of the vaccine was 66% (95% CI: 51%-76%) in children and adolescents, but 47% (25%-63%) in adults, and 53% (20%-72%) in the elderly.

IIV was effective in protecting against influenza like illness.