Surveillance of invasive meningococcal disease in the south of Brazil: considerations of immunization programme.

Invasive meningococcal disease (IMD) is a major cause of meningitis and septicaemia worldwide. The switches in serogroup predominance contribute to the unpredictable nature of the disease with significant health impacts. The aim of this study was to determine the epidemiological profile of IMD in Rio Grande do Sul, Santa Catarina and Paraná, three states in the south of Brazil. All meningitis cases confirmed by clinical and/or laboratory criteria notified to the national information system for notifiable diseases between 2015 and 2019 were analysed. Proportions of serogroup and incidence by age were calculated. A total of 17 894 cases of IMD were reported during this period. Of these, 9029 cases (50 %) were due to serogroup C. Furthermore, serogroup W was responsible for almost half of the cases among children younger than 5 years old during 2017 and 2018, with an overall incidence of 33.3 cases per 100 000 infants. Despite the reduction in serogroup C after the introduction of meningococcal C conjugate vaccine into a childhood immunization programme in Brazil, it remains a significant healthcare issue in the south of the country. Changes in disease epidemiology were observed and serogroup W was the most common among children below 5 years of age in 2017 and 2018. Although future cost-effectiveness studies are necessary, our results could have future implications for meningococcal vaccination programmes.