An updated influenza A(H3N2) vaccine generates limited antibody responses to previously encountered antigens in children

Vaccine. 2018 Jan 29;36(5):758-764. doi: 10.1016/j.vaccine.2017.12.024. Epub 2017 Dec 15.


Background: Influenza vaccination may provide a "back-boost" to antibodies against previously encountered strains. If the back-boost effect is common, this could allow more aggressive vaccine updates, as emerging variants would be expected to both elicit de-novo responses and boost pre-existing responses against recently circulating strains. Here we used the emergence of an antigenically novel A(H3N2) strain to determine whether an antigenically updated vaccine boosted antibodies against historical strains.

Methods: We performed hemagglutination-inhibition (HI) assays on pre- and post-vaccination sera from 124 children 5-17 years old who received 2015-2016 inactivated influenza vaccine, containing an antigenically updated A(H3N2) strain. We evaluated the mean fold increase in HI titer against both the 2015-2016 vaccine strain and representative strains from two prior antigenic clusters. Factors associated with post-vaccination titers against historical strains were evaluated using linear regression, adjusting for baseline titer.

Results: Geometric mean titers against each antigen examined increased significantly after vaccination (P < .0001). Mean fold increase was 3.29 against the vaccine strain and 1.22-1.46 against historical strains. Response to vaccine strain was associated with increased post-vaccination titers against historical strains.

Conclusions: A vaccine containing an antigenically novel A(H3N2) strain modestly boosted antibody responses against historical influenza strains in children.

Keywords: Back-boost; Influenza; Pediatrics; Vaccine.

Publication types

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

MeSH terms

  • Adolescent
  • Antibodies, Viral / blood
  • Antibodies, Viral / immunology*
  • Antigens, Viral / immunology*
  • Child
  • Child, Preschool
  • Cross Reactions / immunology
  • Female
  • Hemagglutination Inhibition Tests
  • Humans
  • Immunogenicity, Vaccine
  • Influenza A Virus, H3N2 Subtype / immunology*
  • Influenza Vaccines / administration & dosage
  • Influenza Vaccines / immunology*
  • Influenza, Human / epidemiology*
  • Influenza, Human / prevention & control*
  • Male
  • Outcome Assessment, Health Care
  • Vaccination


  • Antibodies, Viral
  • Antigens, Viral
  • Influenza Vaccines