Childhood Vaccination and Its Association With Bacterial Meningitis Incidence: Insights From a Pakistani Tertiary Center.

BACKGROUND

Bacterial meningitis is a life-threatening infection in children under five years of age, most commonly caused by Streptococcus pneumoniae, Haemophilus influenzae type b (Hib), and Neisseria meningitidis.

OBJECTIVE

To ascertain the frequency of bacterial meningitis in children who were fully or partially vaccinated according to the national Expanded Program on Immunization (EPI) schedule versus those unvaccinated. Secondary objectives included describing pathogen distribution and demographic characteristics in vaccinated versus unvaccinated children.

METHODOLOGY: A hospital-based cross-sectional study was conducted at the Department of Pediatrics, Mardan Medical Complex, from January to December 2023. Children aged two months to five years with suspected meningitis were enrolled using consecutive sampling. Vaccination status was verified through immunization cards; children with unverifiable vaccination histories were excluded. Children were categorized as fully vaccinated, partially vaccinated (missed some vaccines), or unvaccinated. Data were collected using a structured proforma and analyzed in SPSS version 26 (IBM Corp., Armonk, NY). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association between vaccination and bacterial meningitis. Baseline differences in age and gender were tested statistically (t-test/chi-square), and Fisher's exact test assessed differences in pathogen distribution.

RESULTS

Of 280 enrolled children, 168 (60.0%) were vaccinated (fully or partially) and 112 (40.0%) were unvaccinated. Bacterial meningitis was confirmed in 60 cases (21.4%) by cerebrospinal fluid analysis, with a significantly lower frequency among vaccinated children (24/168; 14.3%) compared to unvaccinated children (36/112; 32.1%). Unvaccinated children were nearly three times more likely to develop meningitis (OR = 2.85, 95% CI: 1.56-5.21; p = 0.0006). Streptococcus pneumoniae was the most common pathogen (40.0%), followed by Hib (21.7%) and Neisseria meningitidis (13.3%); Gram-negative organisms were less frequent. Pathogen distribution did not differ significantly between vaccinated and unvaccinated groups (Fisher's exact test, p = 0.41). Serotype-specific analysis was not performed.

CONCLUSION

Childhood vaccination according to the national schedule significantly reduces the risk of bacterial meningitis, with unvaccinated children nearly three times more vulnerable. Strengthening vaccine coverage, ensuring timely completion of immunization schedules, and addressing barriers, such as limited access, vaccine hesitancy, and administration by undertrained personnel (e.g., teachers, clerks, or newly recruited staff without proper knowledge or training), are essential to reduce disease burden.