Interim vaccine effectiveness against influenza virus among outpatients, France, October 2025 to January 2026
Allan De Clercq, François Blanquart, Vincent Vieillefond, Benoît Visseaux, Alexandra Jacques, Stéphanie Haïm‐Boukobza, Valentin Wehrle, Guillaume Deleglise, Thomas Duret, Sibylle Bernard-Stoecklin, Danielle Perez-Bercoff, Antoine Oblette, Lina Bruno, Marie Anne Rameix-Welti, Laurence Josset, Vincent Enouf, Antonin Bal, on behalf of the RELAB study group
Abstract
In Europe, the 2025/26 seasonal influenza epidemic started in October 2025. Co-circulation of A(H3N2) and A(H1N1)pdm09 was observed in several countries including France. We estimated early vaccine effectiveness (VE) against influenza virus in French outpatients (5,451 positives/18,816 negatives). A significant VE across all age groups was measured: 28% (95% CI: 17-37) for those aged ≥ 65 years, 45% (95% CI: 36-53) for 18-64-year-olds and 57% (95% CIs: 29-74) for 0-17-year-olds. Reinforcing vaccination uptake is warranted.