Inactivated quadrivalent influenza vaccine: time to double the dose in young children?

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  • In children aged 6-17 mo, double-dose inactivated quadrivalent influenza vaccine (IIV4) demonstrated immunogenic noninferiority compared to standard-dose for all strains, with selective superior immunogenicity for B strains in a post hoc analysis.

Why this matters

  • Primary requirement for US licensure criteria was demonstrated, supporting a potential future change in clinical practice toward double-dose IIV4 in all children aged 6 mo and older.

Study design

  • Phase 3, randomized, controlled, observer-blind, multicenter trial.
  • Children aged 6-35 mo (2014-15 season).
  • Vaccinated with investigational double-dose IIV4 or United States-approved standard-dose IIV4.
  • Double-dose contained 15 μg hemagglutinin (HA) of each of: A/California/7/2009 (A/H1N1), A/Texas/50/2012 (A/H3N2), B/Brisbane/60/2008 (B/Victoria), and B/Massachusetts/2/2012 (B/Yamagata).
  • Standard dose contained 7.5 μg of HA of each.
  • Funding: GlaxoSmithKline Biologicals SA.

Key results

  • 2424 children in intent-to-treat cohort.
  • Immunogenic noninferiority of double vs standard dose was demonstrated 28 d after vaccination for all strains in terms of geometric mean titers and seroconversion.
  • Post hoc analysis showed superior immunogenicity for double vs standard dose against B strains in children 6-17 mo of age and unprimed children.
  • Safety and reactogenicity were similar for both doses.