tetano
Editor, Senior Moderator
Vaccine
. 2025 Jun 26:61:127429.
doi: 10.1016/j.vaccine.2025.127429. Online ahead of print. Influenza vaccination in Japanese children, 2024/25: Effectiveness of inactivated vaccine and limited use of newly introduced live-attenuated vaccine
Masayoshi Shinjoh[SUP] 1 [/SUP], Kazuyo Tamura[SUP] 2 [/SUP], Yoshio Yamaguchi[SUP] 3 [/SUP], Hiroyuki Fukushima[SUP] 4 [/SUP], Naoki Kuremoto[SUP] 5 [/SUP], Maika Tezuka[SUP] 6 [/SUP], Naoya Fukushima[SUP] 7 [/SUP], Makoto Yoshida[SUP] 8 [/SUP], Motoko Shimoyamada[SUP] 9 [/SUP], Noriko Suzuki[SUP] 10 [/SUP], Ryo Itaki[SUP] 11 [/SUP], Michiko Chiga[SUP] 12 [/SUP], Ken Kobayashi[SUP] 13 [/SUP], Kenichiro Tsunematsu[SUP] 14 [/SUP], Mitsuhiro Nishida[SUP] 15 [/SUP], Go Yamada[SUP] 16 [/SUP], Akimichi Shibata[SUP] 17 [/SUP], Atsushi Narabayashi[SUP] 18 [/SUP], Akinobu Kamei[SUP] 19 [/SUP], Naonori Maeda[SUP] 20 [/SUP], Yuki Tsumura[SUP] 21 [/SUP], Mizuki Yaginuma[SUP] 22 [/SUP], Munehiro Furuichi[SUP] 23 [/SUP], Chiharu Kawakami[SUP] 24 [/SUP], Satoshi Narumi[SUP] 25 [/SUP], Norio Sugaya[SUP] 26 [/SUP]; Keio Pediatric Influenza Research Group
Affiliations
This study evaluated influenza vaccine effectiveness (VE) among children in Japan during the 2024/25 season, when A(H1N1)pdm09 predominated and live-attenuated influenza vaccine (LAIV) was introduced for the first time. Using a test-negative design, febrile children aged 6 months to 15 years were enrolled from 16 hospitals and 2 clinics. Among 1351 participants, LAIV coverage was low (1.2 %), limiting its VE assessment. In contrast, inactivated influenza vaccine (IIV) coverage was 35 %. The adjusted VE of IIV against influenza A was 73 % (95 % CI: 57-83 %) in inpatients and 57 % (24-75 %) in outpatients. VE was significant in younger age groups. A two-dose regimen provided no additional benefit. The effectiveness observed was consistent with previous seasons and global estimates. While the effectiveness of LAIV was unevaluable due to low coverage, IIV remained effective, supporting its continued use in pediatric populations. LAIV effectiveness should be re-evaluated if coverage increases.
Keywords: Children; Effectiveness; Inactivated vaccine; Influenza; Influenza vaccine; Live vaccine; Test-negative design.
. 2025 Jun 26:61:127429.
doi: 10.1016/j.vaccine.2025.127429. Online ahead of print. Influenza vaccination in Japanese children, 2024/25: Effectiveness of inactivated vaccine and limited use of newly introduced live-attenuated vaccine
Masayoshi Shinjoh[SUP] 1 [/SUP], Kazuyo Tamura[SUP] 2 [/SUP], Yoshio Yamaguchi[SUP] 3 [/SUP], Hiroyuki Fukushima[SUP] 4 [/SUP], Naoki Kuremoto[SUP] 5 [/SUP], Maika Tezuka[SUP] 6 [/SUP], Naoya Fukushima[SUP] 7 [/SUP], Makoto Yoshida[SUP] 8 [/SUP], Motoko Shimoyamada[SUP] 9 [/SUP], Noriko Suzuki[SUP] 10 [/SUP], Ryo Itaki[SUP] 11 [/SUP], Michiko Chiga[SUP] 12 [/SUP], Ken Kobayashi[SUP] 13 [/SUP], Kenichiro Tsunematsu[SUP] 14 [/SUP], Mitsuhiro Nishida[SUP] 15 [/SUP], Go Yamada[SUP] 16 [/SUP], Akimichi Shibata[SUP] 17 [/SUP], Atsushi Narabayashi[SUP] 18 [/SUP], Akinobu Kamei[SUP] 19 [/SUP], Naonori Maeda[SUP] 20 [/SUP], Yuki Tsumura[SUP] 21 [/SUP], Mizuki Yaginuma[SUP] 22 [/SUP], Munehiro Furuichi[SUP] 23 [/SUP], Chiharu Kawakami[SUP] 24 [/SUP], Satoshi Narumi[SUP] 25 [/SUP], Norio Sugaya[SUP] 26 [/SUP]; Keio Pediatric Influenza Research Group
Affiliations
- PMID: 40578174
- DOI: 10.1016/j.vaccine.2025.127429
This study evaluated influenza vaccine effectiveness (VE) among children in Japan during the 2024/25 season, when A(H1N1)pdm09 predominated and live-attenuated influenza vaccine (LAIV) was introduced for the first time. Using a test-negative design, febrile children aged 6 months to 15 years were enrolled from 16 hospitals and 2 clinics. Among 1351 participants, LAIV coverage was low (1.2 %), limiting its VE assessment. In contrast, inactivated influenza vaccine (IIV) coverage was 35 %. The adjusted VE of IIV against influenza A was 73 % (95 % CI: 57-83 %) in inpatients and 57 % (24-75 %) in outpatients. VE was significant in younger age groups. A two-dose regimen provided no additional benefit. The effectiveness observed was consistent with previous seasons and global estimates. While the effectiveness of LAIV was unevaluable due to low coverage, IIV remained effective, supporting its continued use in pediatric populations. LAIV effectiveness should be re-evaluated if coverage increases.
Keywords: Children; Effectiveness; Inactivated vaccine; Influenza; Influenza vaccine; Live vaccine; Test-negative design.