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
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.