Influenza vaccine: FluMist less effective than injected version in children

  • Chung JR et al
  • Pediatrics
  • 7 Jan 2019

  • curated by Liz Scherer
  • Clinical Essentials
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Takeaway

  • Quadrivalent live attenuated vaccine (LAIV4; FluMist) nasal spray is less effective than inactivated influenza vaccine (IIV) injection against influenza A/H1N1 in all pediatric age groups.

Why this matters

  • Findings further confirm efficacy of IIV over LAIV4 for influenza prevention in children.
  • Experts recommend IIV, noting that LAIV4 remains an option for healthy children, >2 years, not otherwise receiving a vaccine.

Key results

  • 17,173 participants from 42 states.
  • Overall, 4244 patients were influenza-positive; 37% (n=1582) influenza A/H3N2, 25% (n=1082) influenza A/H1N1, 12% (n=519) un-subtyped influenza A, 25% (n=1061) influenza B.
  • Combining all seasons, overall vaccine effectiveness (VE) was 51% (95% CI, 47%-54%) for IIV vs 26% (95% CI, 15%-36%) for LAIV4.
  • Against A/H1N1 specifically, VE of IIV, LAIV4, respectively, was 67% (95% CI, 62%-72%) vs 20% (95% CI, 6%-29%).
  • LAIV4 recipients were likelier to contract any influenza vs IIV recipients (OR, 1.48; 95% CI, 1.28-1.70).
  • No significant age distinctions observed, nor did prior season vaccination influence current season VE.

Study design

  • Meta-analysis of 5 observational studies conducted from 2013-2014 through 2015-2016 comparing seasonal VE of IIV to LAIV4 by influenza subtype for children ages 2-4, 5-8, and 9-17 years.
  • Funding: CDC.

Limitations

  • Estimates subject to confounding.
  • Limited ability to assess vaccine priming history influence.