Modelling the impact of a quadrivalent ACWY meningococcal vaccination and vaccination targeting serogroup B in France

Invasive meningococcal disease (IMD) represents a significant global health burden, with high fatality rate and substantial risk of lifelong sequelae. Most cases worldwide are caused by six serogroups (A, B, C, W, X, and Y). Effective vaccines are available to prevent disease caused by serogroups A, B, C, W, and Y. In France, approximately 500 IMD cases occur each year. Since the introduction of mandatory vaccination against serogroup C, the majority of IMD now involve serogroups B, W, and Y. Given these changes in the epidemiology of IMD, French National Authority for Health decided to reconsider its recommendations on meningococcal vaccines. Using an age structured compartmental model describing meningococcal carriage and IMD cases dynamics of serogroups B, W, and Y, we evaluated the expected impact of introducing vaccination against serogroup ACWY or serogroup B on IMD cases in France. Several scenarios were tested to determine the benefits of vaccination at different ages for both ACWY and serogroup B vaccination, in terms of burden reduction and number of vaccinations needed. Under our modelling assumptions we find that for ACWY vaccination the optimal strategy is to target infants and adolescents, supplemented by a catch-up campaign up to the age of 25, which could reduce IMD-W cases by 93 % after 20 years. Five to ten years from the start of the vaccination campaign, focusing only on adolescents may achieve similar outcomes, balancing public health benefits while minimizing costs. For serogroup B vaccination, results showed a limited impact, with the overall reduction of IMD-B cases remaining below 20 % in all studied scenarios, even in the long term. This evaluation informed the discussions of the Technical Vaccination Committee regarding the vaccination strategy for meningococcus and was included in the recommendations of the French National Authority for Health, endorsed by the Ministry of Health.