Trivalent inactivated influenza vaccine effective against influenza A(H3N2) variant viruses in children during the 2014/15 season, Japan

Norio Sugaya, Masayoshi Shinjoh, Chiharu Kawakami, Yoshio Yamaguchi, Makoto Yoshida, Hiroaki Baba, Mayumi Ishikawa, Mio Kono, Shinichiro Sekiguchi, Takahisa Kimiya, Keiko Mitamura, Motoko Fujino, Osamu Komiyama, Naoko Yoshida, Kenichiro Tsunematsu, Atsushi Narabayashi, Yuji Nakata, Akihiro Sato, Nobuhiko Taguchi, Hisayo FujitaMachiko Toki, Michiko Myokai, Ichiro Ookawara, Takao Takahashi

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14 Citations (Scopus)

Abstract

The 2014/15 influenza season in Japan was characterised by predominant influenza A(H3N2) activity; 99% of influenza A viruses detected were A(H3N2). Subclade 3C.2a viruses were the major epidemic A(H3N2) viruses, and were genetically distinct from A/New York/39/2012(H3N2) of 2014/15 vaccine strain in Japan, which was classified as clade 3C.1. We assessed vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children aged 6 months to 15 years by test-negative case-control design based on influenza rapid diagnostic test. Between November 2014 and March 2015, a total of 3,752 children were enrolled: 1,633 tested positive for influenza A and 42 for influenza B, and 2,077 tested negative. Adjusted VE was 38% (95% confidence intervals (CI): 28 to 46) against influenza virus infection overall, 37% (95% CI: 27 to 45) against influenza A, and 47% (95% CI: -2 to 73) against influenza B. However, IIV was not statistically significantly effective against influenza A in infants aged 6 to 11 months or adolescents aged 13 to 15 years. VE in preventing hospitalisation for influenza A infection was 55% (95% CI: 42 to 64). Trivalent IIV that included A/New York/39/2012(H3N2) was effective against drifted influenza A(H3N2) virus, although vaccine mismatch resulted in low VE.

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Keywords

  • Influenza
  • Influenza Virus
  • Laboratory surveillance
  • vaccine and immunization
  • vaccine effectiveness

ASJC Scopus subject areas

  • Epidemiology
  • Public Health, Environmental and Occupational Health
  • Virology

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