Efficacy of live attenuated influenza vaccine in children: A meta-analysis of nine randomized clinical trials.

Nine randomized clinical trials, including approximately 25,000 children aged 6-71 months and 2000 children aged 6-17 years, have evaluated the efficacy of live attenuated influenza vaccine (LAIV) against culture-confirmed influenza as compared to placebo or trivalent inactivated vaccine (TIV). We conducted meta-analyses, based on Mantel-Haenszel relative risks from fixed effect models, to provide an estimate of vaccine efficacy (VE). Relative to placebo, year 1 VE for two doses in vaccine-naïve young children was 77% (95% CI: 72%, 80%; P<0.