Key points

• Flu epidemic characterized by a long duration (12 weeks) and an early onset in mid-December 2024

• Epidemic peak observed in January 2025 (between S01 and S05-2025 depending on the source)

• Atypical co-circulation of the three influenza viruses A(H1N1)pdm09, A(H3N2), and B/Victoria

• Outbreak marked by very high intensity in community practice and hospitals

• One of the most severe epidemics since the last influenza pandemic in 2009

• Excess mortality observed between weeks S01 and S05-2025

• Vaccination coverage across all at-risk groups (52.4%) slightly higher than in the 2023–2024 season (51.5%), but below the 75% target