The Rapid Rebound of Invasive Meningococcal Disease in France at the End of 2022

Background: Invasive meningococcal disease (IMD) cases declined upon the implementation of non-pharmaceutical measures to control the COVID-19 pandemic. A rebound in IMD cases was feared upon easing these measures.Methods: We conducted a retrospective cohort study using the French National Reference Centre Database for meningococci between 2015-2022. We scored serogroups, sex, age groups, and clonal complexes of the corresponding isolates.Findings: Our data clearly show a decline in the number of IMD cases for all serogroups and age groups until 2021. This decline was mainly due to a decrease in IMD cases provoked by the hyperinvasive ST-11 clonal complex. However, since the fall of 2021, there has been an increase in IMD cases, which accelerated in the second half of 2022. This rebound concerned all age groups, in particular 16-24 years. The increase in cases due to serogroups B, W, and Y were mainly due to the expansion of isolates of the ST-7460, the clonal complex ST-9316 strains and the clonal complex ST-23, respectively.Interpretation: IMD epidemiology remains unpredictable and with profound epidemiological changes have been observed. The surveillance of IMD needs to be enhanced using molecular tools. Additionally, vaccination strategies need to be updated to acknowledge recent epidemiological changes.Funding: Institut Pasteur and Santé Publique France.Declaration of Interest: MKT performs contract works for the Institut Pasteur funded by GSK, Sanofi and Pfizer outside the submitted manuscript, and MKT and AED have a patent with GSK, 630133. ST was a recipient of a fellowship from Pfizer that had no role in the data collection, interpretation, or writing of the manuscript. The other authors declare no conflicts of interest.Ethical Approval: These data were collected anonymously as part of the mission of the National Reference Centre for meningococci and Haemophilus influenzae (NRCMHi) for routine surveillance of IMD and isolate identification and typing. The procedure for collecting samples and information was submitted and approved by the CNIL N°1475242/2011 (Commission Nationale de l'Informatique et des Libertés) and the requirement for consent was waived.