Journal Article

Effectiveness of inactivated influenza vaccine in children by vaccine dose, 2013–18

Mitamura, Keiko, Ohnishi, Takuma, Shibata, Meiwa, Furuichi, Munehiro, Sekiguchi, Shinichiro, Yoshida, Makoto, Taguchi, Nobuhiko, Narabayashi, Atsushi, Yamada, Go, Isshiki, Kyohei, Tsunematsu, Kenichiro, Munenaga, Takeshi, Yoshida, Naoko, Sugaya, Norio, Nakamura, Shoko, Yamaguchi, Yoshio, Nakata, Yuji, Kobayashi, Yasuaki, Takahashi, Takao, Maeda, Naonori, Nishida, Mitsuhiro, Shinjoh, Masayoshi, Hirano, Yasuhiro, Araki, Eriko, Ookawara, Ichiro

2019

Overview

•Both one- and two-doses regimens of inactivated flu vac are effective for children.•Both regimens reduced cases involving hospitalization due to influenza A.•The two-dose regimen was more effective against influenza B in some seasons. We assessed the vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) by vaccine dose in children aged 6 months to 12 years for whom two doses are recommended in Japan to ascertain the appropriate vaccine doses. VE was assessed according to a test-negative case-control design based on rapid influenza diagnostic test (RIDT) results. Children aged 6 months to 12 years with a fever ≥38 °C who had received an RIDT in outpatient clinics of 24 hospitals were enrolled for all five seasons since 2013/14. VE by vaccine dose (none vs. once or twice, and once vs. twice) was analyzed. In the dose analysis, 20,033 children were enrolled. Both one- and two-dose regimens significantly reduced cases in preventing any influenza, influenza A, and influenza B, but there was no significant difference in adjusted VE between one- and two-dose regimens overall (adjusted OR, 0.560 [95% CI, 0.505–0.621], 0.550 [95% CI, 0.516–0.586]), 0.549 [95% CI, 0.517–0.583], and 1.014 [95% CI, 0.907–1.135], for none vs. once, none vs. twice, none vs. once or twice, and once vs. twice for any influenza, respectively). Both one- and two-dose regimens significantly reduced cases with any influenza and influenza A every season. Also, both regimens significantly reduced cases of any influenza, influenza A, and influenza B among children aged 1–12 years, especially among those aged 1–5 years. In the 2013/14, 2015/16, and 2016/17 seasons, however, only the two-dose regimen was significantly effective in preventing influenza B. Both one- and two-dose regimens significantly reduced cases involving hospitalization due to any influenza and influenza A. Both one- and two-doses regimens of IIV were effective in preventing influenza for children aged 6 months to 12 years. The two-dose regimen was more effective against influenza B in some seasons.

• Publisher: Elsevier Ltd,Elsevier Limited
• Subject: Age / Allergy and Immunology / Children / Diagnostic systems / Drug dosages / Effectiveness / Fever / Hospitalization / hospitals / Immunization / Influenza / Influenza A / Influenza B / Influenza vaccine / influenza vaccines / Japan / Licenses / Maternal & child health / Ratios / Seasons / Studies / Test-negative case control / Vaccine dose / Vaccine efficacy / Vaccines