Justyna Zawieja

Introduction Invasive meningococcal disease (IMD) caused by meningococcal serogroup B (MenB) is a rare but serious illness with potentially life-threatening outcomes, particularly in infants. In Brazil, IMD is endemic, with the highest incidence in infants and most cases being due to MenB. The four-component MenB vaccine (4CMenB), with potential cross-protection against other meningococcal serogroups, is approved in Brazil for active immunization of individuals aged 2 months to 50 years. This modeling study assessed the public health impact on all age groups in Brazil of introducing routine vaccination with the 4CMenB vaccine in infants aged < 1 year. Methods A static multigenerational multicohort model was developed using a discrete-time Markov approach over a 100-year time horizon. The model incorporates vaccine effectiveness, coverage, and waning rates to estimate the decrease in IMD incidence under the vaccination strategy (2 + 1 schedule at ages 3, 5, and 12 months) evaluated vs. no vaccination. Annual incidence rates of IMD by age group and serogroup between 2007 and 2023, excluding the COVID-19 pandemic period, were retrieved and adjusted for underreporting. Annual IMD-related deaths were calculated from age-specific case fatality rates. Results Assuming 69% cross-protection against serogroup W (MenW), the 4CMenB vaccination of infants would avert 63,038 (− 21%) IMD cases caused by MenB and MenW, and 11,301 (− 20%) deaths in all age groups. The model predicted a reduction of 21,408 (− 43%) MenB cases and 3335 (− 43%) deaths due to MenB in the < 1-year age group. Conclusion This modeling study highlights the considerable public health impact of introducing the 4CMenB vaccine for infants as part of Brazil’s routine vaccination schedule. By reducing IMD morbidity and mortality, routine 4CMenB immunization has the potential to substantially decrease the disease burden, improve long-term health outcomes, and reinforce the potential impact of preventive measures within the national immunization program. Graphical Abstract available for this article. Graphical Abstract