Effectiveness of the 2023 Southern Hemisphere Influenza Vaccine Against Outpatient Influenza-Like Illness: A Multi-Country Test-Negative Design Study.

ABSTRACT:

Background

Routine monitoring of seasonal influenza vaccine effectiveness (VE) across multiple countries is essential to understand the performance of seasonal vaccine programs.

Methods

Using a test-negative study design, we estimated the effectiveness of the 2023 Southern Hemisphere formulation of the seasonal influenza vaccine in preventing outpatient medically attended influenza-like illness (ILI) in Australia, South Africa, and Thailand. Sentinel surveillance systems identified patients presenting with ILI who were tested by RT-PCR for influenza. VE was estimated as one minus the odds ratio comparing the vaccination status of test-positive cases and test-negative non-cases. Models adjusted for country, patients' age group, sex, underlying medical conditions, and calendar

SUBMITTER: Regan AK 

PROVIDER: S-EPMC12484440 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature