Effectiveness of Intranasal Live Attenuated Influenza Vaccine Against All-cause Acute Otitis Media in Children

Abstract

Acute otitis media (AOM) is a frequent complication of influenza in children, and influenza vaccination helps protect against influenza-associated AOM. A live attenuated influenza vaccine (LAIV) approved for eligible children aged ≥2 years for the prevention of influenza also effectively reduces influenza-associated AOM. However, the annual effectiveness of LAIV against all-cause AOM is unknown. AOM rates in children aged 6-83 months from 6 randomized, placebo-controlled trials and 2 randomized, inactivated influenza vaccine-controlled trials were pooled and analyzed. To enable comparison with studies of AOM prevention by pneumococcal conjugate vaccines, 12-month effectiveness was calculated assuming that LAIV had no effect outside of influenza seasons. During influenza seasons, LAIV efficacy compared with placebo against all-cause AOM in children aged 6-71 months (N = 9497) was 12.4% (95% confidence interval [CI]: 2.0%, 21.6%) in year 1. In year 2, the efficacy in children aged 18-83 months (N = 4142) was 6.2% (95% CI: -12.4%, 21.7%). Compared with inactivated influenza vaccine, the efficacy of LAIV in children aged 6-71 months (N = 9901) against febrile all-cause AOM was 9.7% (95% CI: -2.1%, 20.1%). The estimated 12-month effectiveness of LAIV compared with placebo against all-cause AOM was 7.5% (95% CI: -2.4%, 16.2%). LAIV reduced the incidence of all-cause AOM compared with placebo in children. The estimated 12-month effectiveness of LAIV was comparable with 7-valent pneumococcal conjugate vaccine. The effects of the vaccines will overlap somewhat; however, because pneumococcal conjugate vaccines only prevent a fraction of all pneumococcal AOM and influenza-associated AOM can be caused by other pathogens, LAIV could further reduce the incidence of AOM in children.