Cell-Mediated Immunity Against Antigenically Drifted Influenza A(H3N2) Viruses in Children During a Vaccine Mismatch Season

J Infect Dis. 2016 Oct 1;214(7):1030-8. doi: 10.1093/infdis/jiw311. Epub 2016 Aug 17.

Abstract

Background: Emergence of antigenically drifted influenza A(H3N2) viruses resulted in reduced vaccine effectiveness in all age groups during the 2014-2015 influenza season. In children, inactivated influenza vaccine (IIV) elicited neutralizing antibodies (Abs) against drifted strains at significantly lower levels than against the vaccine strain. Little is known about the cross-reactivity of cell-mediated immunity against drifted strains in children.

Methods: Children aged 3-17 years (n = 48) received IIV during the 2014-2015 influenza season. Peripheral blood mononuclear cells, collected before (on day 0) and after (on days 7 and 21) vaccination were evaluated for induction of cross-reactive plasmablasts, memory B cells, and cytokine-secreting CD4(+) and CD8(+) T cells against the vaccine and drifted A(H3N2) viruses by an enzyme-linked immunospot assay and flow cytometry.

Results: IIV increased frequencies of plasmablasts and memory B cells. The overall induction of the T-cell response was not significant. Both B-cell and T-cell responses showed significant cross-reactivity against A(H3N2) viruses. Age and preexisting immunity affected virus-specific plasmablast responses and fold-change of T-cell responses, respectively. The proportion of T-helper type 1-prone (ie, interferon γ- or tumor necrosis factor α-secreting) CD4(+) T cell responses also increased with age.

Conclusions: In children aged 3-17 years, B- and T-cell responses following IIV receipt showed significant cross-reactivity against A(H3N2) viruses during a vaccine mismatch season.

Keywords: A(H3N2) drifted viruses; antigenic mismatch; cell-mediated immunity; influenza vaccines; young and adolescent children.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • B-Lymphocytes / immunology*
  • Child
  • Child, Preschool
  • Cross Reactions
  • Female
  • Genetic Drift*
  • Humans
  • Immunity, Heterologous*
  • Influenza A Virus, H3N2 Subtype / genetics
  • Influenza A Virus, H3N2 Subtype / immunology*
  • Influenza, Human / immunology*
  • Influenza, Human / virology*
  • Male
  • T-Lymphocytes / immunology*