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. doi: 10.1016/j.vaccine.2015.11.010. Epub 2015 Nov 14.


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.

Keywords: LAIV; Pediatrics; Quadrivalent live attenuated influenza vaccine.

Publication types

  • Observational Study

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Influenza Vaccines / administration & dosage*
  • Influenza Vaccines / immunology*
  • Influenza, Human / epidemiology*
  • Influenza, Human / prevention & control*
  • Male
  • Treatment Outcome
  • United States / epidemiology
  • Vaccines, Attenuated / administration & dosage
  • Vaccines, Attenuated / immunology
  • Vaccines, Inactivated / administration & dosage
  • Vaccines, Inactivated / immunology


  • Influenza Vaccines
  • Vaccines, Attenuated
  • Vaccines, Inactivated