Influenza vaccination in Japanese children, 2024/25: Effectiveness of inactivated vaccine and limited use of newly introduced live-attenuated vaccine
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.
Authors
- Naonori Maeda (ORCID: https://orcid.org/0000-0001-8799-288X)
- Masayoshi Shinjoh (ORCID: https://orcid.org/0000-0002-6291-7186)
- Munehiro Furuichi (ORCID: https://orcid.org/0000-0001-7742-1135)
- Kazuyo Tamura
- Go Yamada (ORCID: https://orcid.org/0000-0003-3122-2418)
- Satoshi Narumi (ORCID: https://orcid.org/0000-0002-0940-4517)
- Motoko Shimoyamada
- Mitsuhiro Nishida (ORCID: https://orcid.org/0000-0003-2016-3598)
- Kenichiro Tsunematsu
- Akinobu Kamei
- Hiroyuki Fukushima (ORCID: https://orcid.org/0000-0003-3869-9892)
- Norio Sugaya
- Atsushi Narabayashi (ORCID: https://orcid.org/0000-0002-5274-8104)
- Yuki Tsumura
- M. Tezuka
- Yoshio Yamaguchi (ORCID: https://orcid.org/0000-0003-4144-8760)
- Naoya Fukushima (ORCID: https://orcid.org/0000-0003-3255-7527)
- Michiko Chiga (ORCID: https://orcid.org/0000-0002-0346-9352)
- Mizuki Yaginuma (ORCID: https://orcid.org/0000-0002-6335-360X)
- K. Kobayashi
- Noriko Suzuki
- Makoto Yoshida (ORCID: https://orcid.org/0000-0002-2846-2069)
- Ryo Itaki
- Akimichi Shibata
- Chiharu Kawakami
- Naoki Kuremoto
Institutions
- Keio University (JP)
- Saitama Prefecture (JP)
- Hiratsuka City Hospital (JP)
- Ashikaga Red Cross Hospital (JP)
- Shizuoka City Shimizu Hospital (JP)
- National Center for Global Health and Medicine (JP)
- Tokyo Medical Center (JP)
- Tokyo Dental College Ichikawa General Hospital (JP)
- Keio University Hospital (JP)
- Kawasaki Municipal Hospital (JP)
- Sapporo Kosei General Hospital (JP)
- Nagano Municipal Hospital (JP)
- Saitama Municipal Hospital (JP)
- Yokohama Municipal Citizen's Hospital (JP)
- Fuji Heavy Industries Health Insurance Society Ota Memorial Hospital (JP)
- Kawasaki Hospital (JP)
- Otsuka Pharmaceutical (Spain) (ES)
- keiyu Hospital (JP)
- Tochigi Medical Center (JP)
- Social Insurance Saitama Chuo Hospital (JP)
Publication Details
- Journal
- Vaccine
- Published
- 2025-06-27
- DOI
- https://doi.org/10.1016/j.vaccine.2025.127429
- Citations
- 4
- Primary Topic
- Influenza Virus Research Studies
- Type
- article
- Field-Weighted Citation Impact
- 5.42