Effectiveness of live attenuated influenza vaccine and inactivated influenza vaccine in children 2-17 years of age in 2013-2014 in the United States.

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Effectiveness of live attenuated influenza vaccine and inactivated influenza vaccine in children 2-17 years of age in 2013-2014 in the United States.

Vaccine. 2016 Jan 2;34(1):77-82

Authors: Caspard H, Gaglani M, Clipper L, Belongia EA, McLean HQ, Griffin MR, Talbot HK, Poehling KA, Peters TR, Veney N, Ambrose CS

Abstract
BACKGROUND: A postmarketing observational study was initiated to evaluate quadrivalent live attenuated influenza vaccine (LAIV) effectiveness in children aged 2-17 years in the United States.
METHODS: Children and adolescents aged 2-17 years seeking outpatient care for febrile acute respiratory illness <5 days duration were enrolled at 4 geographically diverse sites during the 2013-2014 influenza season. Nasal swabs were tested for influenza using reverse transcription polymerase chain reaction. Vaccination status was documented from medical records or immunization registries. Children who received ≥1 dose of influenza vaccine ≥14 days before study visit were considered vaccinated. Vaccine effectiveness (VE) was estimated as 100×(1-adjusted odds ratio), where the odds of interest are the odds of vaccine exposure among influenza cases and test-negative controls.
RESULTS: In total, 1033 children and adolescents were included in the analysis. Influenza was detected in 14% (145/1033) of all children, with 74% (108/145) of the influenza cases due to A/H1N1pdm09 strains, 21% (31) to influenza B, and 4% (6) to influenza H3N2. LAIV did not show significant effectiveness against A/H1N1pdm09 (VE 13% [95% CI: -55 to 51]) but was effective against B/Yamagata strains (82% [95% CI: 12-96]). Inactivated influenza vaccine was effective against A/H1N1pdm09 (74% [95% CI: 50-86]) and B/Yamagata (70% [95% CI: 18-89]).
CONCLUSIONS: LAIV provided significant protection against B/Yamagata influenza but not against A/H1N1pdm09 in children aged 2-17 years in 2013-2014, resulting in a proposed change of the 2015-2016 formulation with a new and more heat-stable A/H1N1pdm09 LAIV strain.

PMID: 26589519 [PubMed - indexed for MEDLINE]

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