tetano
Editor, Senior Moderator
accine
. 2026 Oct 28:96:129273.
doi: 10.1016/j.vaccine.2026.129273. Online ahead of print.
Jiaojiao Zhang 1 , Ying Shen 1 , Weixian Shi 1 , Jiaxin Ma 1 , Jiachen Zhao 1 , Chunna Ma 1 , Dan Wu 1 , Yingying Wang 1 , Guilan Lu 1 , Lu Zhang 1 , Yimeng Liu 1 , Wei Duan 1 , Weijia Zhang 1 , Xiaodi Hu 1 , Hui Xu 1 , Quanyi Wang 2 , Peng Yang 3 , Daitao Zhang 4
Affiliations Expand
Introduction: This study aimed to estimate the end-of-season influenza vaccine effectiveness (VE) against A(H3N2) and B/Victoria in the 2025/26 season in Beijing, China.
Methods: We used a test-negative design to assess influenza VE among outpatients with influenza-like illness (ILI) enrolled through the Beijing influenza sentinel virological surveillance system from September 2025 (week 40/2025) to May 2026 (week 21/2026). Cases were ILI patients who tested positive for influenza; controls were those who tested negative. The VE was estimated using non-conditional multiple logistic regression models, adjusting for age (modelled as a natural cubic spline), sex, presence of comorbidities, area of residence, and calendar week (modelled as a natural cubic spline).
Results: Among 20,749 ILI patients tested, 4875 (23.5%) were positive for influenza, with A(H3N2) and B/Victoria being the predominant strains. Adjusted VE was 26.4% (95% CI: 17.8 to 34.1) against any influenza, 22.2% (95% CI: 11.3 to 31.7) against A(H3N2), and 34.7% (95% CI: 19.6 to 47.0) against B/Victoria, with the highest VE observed in adults aged 18-59 years (53.0%, 95%CI: 37.0 to 64.9) against any influenza. The adjusted VE was similar for those vaccinated in 2025/26 only (38.7%, 95%CI: 15.6 to 55.5) or both 2024/25 and 2025/26 seasons (35.1%, 95%CI: 16.5 to 49.6), but higher than those vaccinated in 2024/25 only (17.0%, 95%CI: -16.1 to 40.7) among B/Victoria. For A(H3N2), the VE point estimate was higher among those vaccinated in the 2025/26 season only (27.9%, 95%CI: 11.5 to 41.2) than among those vaccinated in both seasons (17.9%, 95%CI: 4.0 to 29.7) and 2024/25 only (-6.1%, 95%CI: -28.7 to 12.5).
Conclusion: Our findings indicate that seasonal vaccination reduced laboratory-confirmed influenza among outpatients by approximately a quarter, with higher VE in adults aged 18-59 years. VE estimates according to vaccination status over two consecutive seasons showed different patterns for A(H3N2) and B/Victoria. These real-world findings support the ongoing public health value of influenza vaccination and highlight the importance of continuous virological surveillance, prevention, and control policy.
Keywords: Influenza; Influenza-like illness; Vaccine effectiveness.
. 2026 Oct 28:96:129273.
doi: 10.1016/j.vaccine.2026.129273. Online ahead of print.
End-of-season influenza vaccine effectiveness against a(H3N2) and B/Victoria in Beijing, China, 2025/26 season
Jiaojiao Zhang 1 , Ying Shen 1 , Weixian Shi 1 , Jiaxin Ma 1 , Jiachen Zhao 1 , Chunna Ma 1 , Dan Wu 1 , Yingying Wang 1 , Guilan Lu 1 , Lu Zhang 1 , Yimeng Liu 1 , Wei Duan 1 , Weijia Zhang 1 , Xiaodi Hu 1 , Hui Xu 1 , Quanyi Wang 2 , Peng Yang 3 , Daitao Zhang 4
Affiliations Expand
- PMID: 42950746
- DOI: 10.1016/j.vaccine.2026.129273
Abstract
Introduction: This study aimed to estimate the end-of-season influenza vaccine effectiveness (VE) against A(H3N2) and B/Victoria in the 2025/26 season in Beijing, China.
Methods: We used a test-negative design to assess influenza VE among outpatients with influenza-like illness (ILI) enrolled through the Beijing influenza sentinel virological surveillance system from September 2025 (week 40/2025) to May 2026 (week 21/2026). Cases were ILI patients who tested positive for influenza; controls were those who tested negative. The VE was estimated using non-conditional multiple logistic regression models, adjusting for age (modelled as a natural cubic spline), sex, presence of comorbidities, area of residence, and calendar week (modelled as a natural cubic spline).
Results: Among 20,749 ILI patients tested, 4875 (23.5%) were positive for influenza, with A(H3N2) and B/Victoria being the predominant strains. Adjusted VE was 26.4% (95% CI: 17.8 to 34.1) against any influenza, 22.2% (95% CI: 11.3 to 31.7) against A(H3N2), and 34.7% (95% CI: 19.6 to 47.0) against B/Victoria, with the highest VE observed in adults aged 18-59 years (53.0%, 95%CI: 37.0 to 64.9) against any influenza. The adjusted VE was similar for those vaccinated in 2025/26 only (38.7%, 95%CI: 15.6 to 55.5) or both 2024/25 and 2025/26 seasons (35.1%, 95%CI: 16.5 to 49.6), but higher than those vaccinated in 2024/25 only (17.0%, 95%CI: -16.1 to 40.7) among B/Victoria. For A(H3N2), the VE point estimate was higher among those vaccinated in the 2025/26 season only (27.9%, 95%CI: 11.5 to 41.2) than among those vaccinated in both seasons (17.9%, 95%CI: 4.0 to 29.7) and 2024/25 only (-6.1%, 95%CI: -28.7 to 12.5).
Conclusion: Our findings indicate that seasonal vaccination reduced laboratory-confirmed influenza among outpatients by approximately a quarter, with higher VE in adults aged 18-59 years. VE estimates according to vaccination status over two consecutive seasons showed different patterns for A(H3N2) and B/Victoria. These real-world findings support the ongoing public health value of influenza vaccination and highlight the importance of continuous virological surveillance, prevention, and control policy.
Keywords: Influenza; Influenza-like illness; Vaccine effectiveness.