Childhood Bacterial Meningitis Surveillance in Southern Vietnam: Trends and Vaccination Implications from 2012 to 2021

Background This retrospective hospital-based surveillance aimed to assess the epidemiology, causative pathogens trend, and serotypes distribution of pneumococcal meningitis among children aged under five years with bacterial meningitis in southern Vietnam after the introduction of pentavalent vaccine in the Expanded Program on Immunization (EPI). Methods From 2012 to 2021, cerebrospinal fluid samples were collected from children aged under five years with suspected bacterial meningitis at Children's Hospitals 1 and 2 in Ho Chi Minh City. Probable bacterial meningitis (PBM) cases were identified using biochemistry and cytology. Real-time Polymerase Chain Reaction was used to confirm cases of confirmed bacterial meningitis (CBM) caused by Streptococcus pneumoniae, Haemophilus influenzae, or Neisseria meningitidis. S. pneumoniae serotyping was performed. Results Of the 2,560 PBM cases, 158 (6.2%) were laboratory-confirmed. The CBM proportion decreased during the 10-year study and was associated with age, seasonality, and permanent residence. S. pneumoniae was the most common pathogen causing bacterial meningitis (86.1%), followed by H. influenzae (7.6%) and N. meningitidis (6.3%). The case fatality rate was 8.2% (95% confidence interval: 4.2%-12.2%). Pneumococcal serotypes 6A/B, 19F, 14, and 23F were the most prevalent, and the proportion of pneumococcal meningitis cases caused by the 10-valent pneumococcal conjugate vaccine (PCV) serotypes decreased from 96.2% to 57.1% during the PCV eras. Conclusions S. pneumoniae is the most frequent causative agent of bacterial meningitis in children aged under five years in southern Vietnam over the last decade. Policymakers may need to consider introducing PCVs into the EPI to effectively prevent and control bacterial meningitis.