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

Abstract

Background: This retrospective hospital-based surveillance aimed to assess the epidemiology, causative pathogens trend, and serotypes distribution of pneumococcal meningitis among children aged under 5 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 5 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. Streptococcus pneumoniae serotyping was performed.

Results: Of the 2560 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. Streptococcus 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: Streptococcus pneumoniae is the most frequent causative agent of bacterial meningitis in children aged under 5 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.

Keywords: Vietnam; childhood bacterial meningitis; epidemiology; surveillance; vaccination implications.

Graphical Abstract

Figure 1.

Summary of bacterial meningitis case recruitment and diagnostic testing performed over 10 years, from 2012 to 2021.

Figure 2.

The bacterial meningitis positivity rate and pathogens distribution by month and year. (A) The yearly trend of pathogens causing bacterial meningitis. (B) Distribution of bacterial meningitis positivity by seasonality: meningitis cases were more prevalent during the dry season (from November to April) compared to the rainy season (May to October) (positivity 60.8% vs 39.2%; P < .001). (C) Distribution of pathogens causing bacterial meningitis and the Hemophilus influenzae type b (Hib) coverage rate by year. The Hib coverage rate data were obtained from the Expanded Program on Immunization unit in Southern Vietnam. Streptococcus pneumoniae was the primary causative pathogen of bacterial meningitis cases over the last 10 decades in Southern Vietnam.

Figure 3.

Distribution of serotypes causing pneumococcal meningitis during the pneumococcal conjugate vaccine (PCV) eras. (A) The cases, death cases, and sequelae cases of pneumococcal meningitis caused by the PCV10 serotypes by the PCV eras. Two linear-by-linear associations were observed between the pneumococcal meningitis cases caused by the PCV10 serotypes and the PCV eras (P = .032) as well as the pneumococcal meningitis sequelae cases caused by the PCV10 serotypes and the PCV eras (P = .02). (B) The nonvaccine serotypes (NVT) pneumococcal meningitis cases, death cases, and sequelae cases by the PCV eras. The proportion of NVT pneumococcal meningitis cases and sequelae cases increased from 0% in the pre-PCV era to 14.3% in the PCV10 era and 50% in the PCV13 era. There were nonlinear-by-linear association tests (P = .0779 and P = .512).