Key Points

• An increase in the number of cases of invasive meningococcal disease (IMD) was observed in France and Nouvelle-Aquitaine during the 2024–2025 season, which may be partly linked to the particularly severe influenza epidemic during that season. Indeed, it has been shown that influenza virus infections can increase the risk of IMD.

• The number of reported cases has been particularly high over the past two months, with a peak in February 2025 that was significantly higher than the previous highest peak observed in the region (in December 2023).

• Presence of IIM linked to three serogroups (B, W, and Y) in the region.

• An upward trend in the number of cases among infants under 1 year of age over the past two seasons.

• A total of 8 deaths were reported in Nouvelle-Aquitaine during the 2024–2025 season, half of which occurred in 2025.