Influenza vaccine effectiveness and genetic diversity: insights from end-of-season community surveillance, France, 2024-2025.

ABSTRACT: Influenza 2024-2025 season in France was characterized by prolonged duration, unusual co-circulation of all three viruses (A(H1N1)pdm09, A(H3N2), B/Victoria) with several subclades, and substantial healthcare impact. We aimed to investigate the impact of influenza genetic diversity on vaccine effectiveness (VE). A test-negative design study was conducted to estimate VE in a large cohort from the RELAB network of community-based laboratories (n = 77,704 patients). A subset of sequenced samples (n = 2,119 patients) allowed VE estimation for several clades and subclades as well as comparison of subclade distribution by vaccination status. Vaccine coverage was 45% in patients aged 65 years and older (65+). VE based on PCR-confirmed infections was 44% (95% CI: 41-48%) and lower in 65+ individua

SUBMITTER: Clercq A 

PROVIDER: S-EPMC12517415 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature