Invasive meningococcal infections: a high number of cases in January and February 2025
The start of the 2024–2025 season has been marked by a particularly high number of cases of invasive meningococcal disease. Santé publique France has released the number of cases reported as of March 7, 2025, and reiterates the importance of vaccination for infants, as well as for adolescents and young adults for certain serogroups.
Invasive meningococcal infections
thematic dossier
Invasive meningococcal infections are associated with significant morbidity and mortality. Reporting and surveillance of these infections are intended to strengthen prevention efforts against this...
Invasive meningococcal infections (IMIs) are bacterial infections caused by meningococcus. They can lead to meningitis or sepsis. Other clinical forms have also been described, such as arthritis or forms with gastrointestinal symptoms. These are very serious infections that can lead to death in 10 to 12% of cases and to long-term complications in 20 to 25% of cases.
Santé publique France has issued an alert regarding the resurgence of IIM cases observed in January 2025 (95 cases reported as of March 7, 2025) amid the flu epidemic. This resurgence continued into February 2025, with 89 cases reported as of March 7, 2025 (provisional data), a level significantly higher than what was observed during the same period in previous seasons.
Number of cases of invasive meningococcal disease per month and per season (January and February 2025: preliminary data, cases reported as of March 7, 2025)
In this context, Santé publique France is warning of the risk of spatio-temporal clusters of cases that may be linked to the circulation of clonal strains. Two clusters of IIM B have already been identified since the beginning of the year:
among students in Lyon in January 2025. Vaccination against IIM B was recommended for students at a university of applied sciences.
in Rennes between December 2024 and February 2025, with 6 cases caused by the same bacterial strain in two separate settings (a family and students) with no connection between them. A vaccination campaign against IIM B is being organized by the Brittany Regional Health Agency to vaccinate young people aged 15 to 24 who live, attend school, study, or work in the Rennes Métropole area.
These situations highlight the transmission potential and virulence of IIM B. The rapid detection of spatio-temporal clusters of cases allows for the implementation of targeted vaccination efforts.
Furthermore, meningococcal B infections linked to serogroups W and Y have been on the rise since 2022 and have prompted new vaccination recommendations effective January 1, 2025, targeting infants and adolescents, as well as catch-up vaccination for those up to age 24.
The 2024 IIM surveillance report will be published in the second quarter of 2025.
Reminder of Meningococcal Vaccination Recommendations
Infants: As of January 1, 2025, vaccination of all infants against meningococcal B and against meningococcal ACWY is mandatory.
Adolescents: Vaccination against meningococcal ACWY is recommended between the ages of 11 and 14, with catch-up vaccination available up to age 24. This catch-up vaccination is essential to directly protect young adults and also serves a public health goal by reducing transmission within the population.
Vaccination Information Service
What are vaccines for? How do they work? At what age should children be vaccinated? Vaccination-info-service.fr answers the most frequently asked questions about vaccination. A separate...
Vaccination
thematic dossier
Contagious diseases most often affect children at a very young age. Because children are particularly vulnerable, they are a priority target for vaccination programs.
