Influenza vaccine effectiveness against influenza-related medical visits, hospitalization and death among adults aged 65 years and older in Taiwan: interim 2024-2025 season result using standard-dose inactivated influenza vaccine.

Authors

Tsung-Pei Tsou, Yi-Ting Huang, Chieh-Yu Lin, Po-Wei Chu, Yen-Tsung Huang

Published in

Vaccine. Volume 93. Pages 129165. Sep 29, 2026. Epub Sep 29, 2026.

Abstract

The 2024-2025 influenza season in Taiwan was notably more severe than the prior season, with severe cases increasing from 1433 to 2215 and deaths increasing from 297 to 545. Vaccination coverage among adults aged ≥65 years also declined from 53.6% to 48.1%. All government-funded vaccines in the 2024-2025 season were inactivated standard-dose trivalent influenza vaccines. This study aimed to evaluate interim vaccine effectiveness (VE) in this high-burden season.
Building upon a validated methodological framework from our previous research, we employed a multi-database linkage approach to conduct a population-based cohort study among adults aged ≥65 years in Taiwan from October 1, 2024 through February 15, 2025. We assessed VE against laboratory-confirmed influenza outcomes, adjusting for age, sex, and pre-existing comorbidities through multivariable logistic regression. Index-date aligned propensity score matching was used as sensitivity analysis.
Despite a decline in vaccination coverage, the vaccine demonstrated robust protection against severe outcomes. The adjusted VE was 71.9% (95% CI: [63.0-78.8]) against 30-day mortality and 70.0% (95% CI: [62.1-76.2]) against ICU admissions. Protection against influenza-associated hospitalizations was 58.2% (95% CI: [52.9-62.9]), while VE against outpatient visits was 44.8% (95% CI: [42.4-47.1]). Propensity score matching showed similar trend but generally lower VE estimates.
Our findings confirm that the influenza vaccine remains highly effective in preventing severe outcomes, despite the reduced population uptake and increased disease burden. The methodology, consistent with our prior season's analysis, underscores the reliability of these results. We conclude that enhancing vaccination coverage among the elderly is critical to mitigating the impact of severe seasonal epidemics.

PMID:
42810173
Bibliographic data and abstract were imported from PubMed on 30 Sep 2026.

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