Elsevier

Vaccine

Volume 30, Issue 5, 20 January 2012, Pages 886-892
Vaccine

The efficacy of intranasal live attenuated influenza vaccine in children 2 through 17 years of age: A meta-analysis of 8 randomized controlled studies

https://doi.org/10.1016/j.vaccine.2011.11.104Get rights and content
Under a Creative Commons license
open access

Abstract

Background

Nine randomized controlled clinical trials, including approximately 26,000 children aged 6 months to 17 years, have evaluated the efficacy of live attenuated influenza vaccine (LAIV) against culture-confirmed influenza illness compared with placebo or trivalent inactivated influenza vaccine (TIV). The objective of the current analysis was to integrate available LAIV efficacy data in children aged 2–17 years, the group for whom LAIV is approved for use.

Methods

A meta-analysis was conducted using all available randomized controlled trials and a fixed-effects model. Cases caused by drifted influenza B were analyzed as originally classified and with all antigenic variants classified as dissimilar.

Results

Five placebo-controlled trials (4 were 2-season trials) and 3 single-season TIV-controlled trials were analyzed. Compared with placebo, year 1 efficacy of 2 doses of LAIV was 83% (95% CI: 78, 87) against antigenically similar strains; efficacy was 87% (95% CI: 78, 93), 86% (95% CI: 79, 91), and 76% (95% CI: 63, 84) for A/H1N1, A/H3N2, and B, respectively. Classifying B variants as dissimilar, efficacy against all similar strains was 87% (95% CI: 83, 91) and 93% (95% CI: 83, 97) against similar B strains. Year 2 efficacy was 87% (95% CI: 82, 91) against similar strains. Compared with TIV, LAIV recipients experienced 44% (95% CI: 28, 56) and 48% (95% CI: 38, 57) fewer cases of influenza illness caused by similar strains and all strains, respectively. LAIV efficacy estimates for children from Europe, the United States, and Middle East were robust and were similar to or higher than those for the overall population.

Conclusions

In children aged 2–17 years, LAIV demonstrated high efficacy after 2 doses in year 1 and revaccination in year 2, and greater efficacy compared with TIV. This meta-analysis provides precise estimates of LAIV efficacy among the approved pediatric age group.

Highlights

► LAIV efficacy in children 2–17 years was examined in 8 randomized controlled trials. ► Compared with placebo, LAIV efficacy was 78%–87% in years 1 and 2. ► Similar efficacy was observed against each type/subtype (A/H1N1, A/H3N2, and B). ► Compared with TIV recipients, LAIV recipients had 44%–50% less influenza illness. ► These data provide precise efficacy estimates for the approved pediatric age group.

Abbreviations

AOM
acute otitis media
LAIV
live attenuated influenza vaccine
RR
relative risk
TIV
trivalent inactivated influenza vaccine

Keywords

Influenza vaccine
Child
Live attenuated influenza vaccine
Trivalent inactivated influenza vaccine
Meta-analysis
Vaccine efficacy

Cited by (0)