The Efficacy of Live Attenuated Influenza Vaccine Against Influenza-associated Acute Otitis Media in Children

Background: Acute otitis media (AOM) is a frequent complication of influenza in young children. Influenza vaccination is known to protect against AOM by preventing influenza illness. We sought to determine the efficacy of the live attenuated influenza vaccine (LAIV) against influenza-associated AOM compared with placebo and trivalent inactivated influenza vaccine (TIV). LAIV is approved for eligible children aged >= 2 years in the United States and in several other countries. Methods: AOM incidence data from 6 randomized, double-blind, placebo-controlled trials and 2 randomized, double-blind, TIV-controlled trials in children 6 to 83 months of age were pooled and analyzed. Results: A total of 290 cases of AOM were identified in 24,046 study subjects. LAIV efficacy against influenza-associated AOM was 85.0% (95% confidence interval [CI], 78.3%-89.8%) compared with placebo and 54.0% (95% CI, 27.0%- 71.7%) compared with TIV. Efficacy trended higher in those >= 24 months of age compared with those aged 6 to 23 months. In placebo-controlled trials, among children who acquired influenza despite vaccination, AOM was diagnosed in 10.3% of LAIV recipients and 16.8% of placebo recipients, representing a 38.2% (95% CI, 11.0%-58.2%) relative reduction in the development of AOM. In TIV-controlled studies, among subjects with breakthrough influenza illness, the proportions of LAIV and TIV recipients who developed AOM were similar. Conclusions: Children receiving LAIV had a high level of protection against influenza-associated AOM when compared with placebo or TIV. This was most evident in children older than 2 years, for whom LAIV is indicated. LAIV recipients who contracted breakthrough influenza illness despite vaccination developed AOM at a significantly lower rate than did unvaccinated children who developed influenza.