Analysis of Serotypes Isolated in Bacterial Meningitis Cases and Potential Impact of Immunization in Belo Horizonte, 2024

Pneumococcus and meningococcus are the main agents responsible for vaccine-preventable meningitis. Expanded coverage of pneumococcal conjugate vaccination in infants has indirectly protected the unvaccinated population but has increased the occurrence of serotypes not included in the vaccine. Regarding meningococcal disease, vaccination has globally reduced its incidence. This study aimed to characterize vaccine-preventable meningitis in Belo Horizonte, estimating the potential prevention afforded by currently available conjugate vaccines. Cross-sectional study of confirmed meningitis cases in the Notifiable Diseases Information System (SINAN) of the Ministry of Health, in residents of Belo Horizonte with symptom onset between January and December 2024, whose final classification was meningococcal or pneumococcal meningitis. Serotypes and genogroups of culture-isolated cases were identified by the State Reference Laboratory. In 2024, 714 suspected meningitis cases were reported among residents of Belo Horizonte, of which 36 were caused by pneumococcus and six by meningococcus. For pneumococcus, one case each of serotypes 3, 6C, 9N, 11A, 18A, and 28A and two cases each of 12F, 14, and 19A were identified. The Pn10 vaccine would potentially impact only serotype 14. Use of Pn13 in children would expand the impact to 5 (41.7%) cases, and Pn20 would impact 8 (66.7%) cases. For meningococcus, three cases were caused by genogroup C, two by Y, and one by W. The MenC vaccine would potentially protect against half of the cases, and the quadrivalent vaccine against all cases. Only one pneumococcal meningitis case would be impacted by the pneumococcal vaccine currently available in the National Immunization Program (PNI) for infants. Use of broader-spectrum vaccines could impact up to three-quarters of meningitis cases by this etiology, considering direct or indirect protection. For meningococcus, achieving high coverage with the quadrivalent vaccine in adolescents, already recommended by the PNI, is essential to reduce circulation of all identified genogroups.