Meningitis Burden and Vaccine Impact in the WHO Western Pacific Region, 1990–2023

Abstract Background Meningitis remained a major cause of death and disability worldwide, but evidence on long-term trends, pathogen distribution, and the impacts of the vaccine program across the WHO Western Pacific Region (WPR) remained limited. Methods We used the World Health Organization Immunization Data and the Global Burden of Diseases Study (GBD) 2023 for the period 1990-2023. We assessed the incidence and mortality of meningitis across 32 WPR countries. Incidence and mortality were analyzed by age, sex, and 17 pathogens, with age-standardized rates calculated using the GBD global standard population. To evaluate the impact of the vaccine program, we applied negative binomial generalized linear models with a log link function and population offset to annual pathogen-specific death counts, characterizing vaccine exposure by program introduction and annual coverage. Results From 1990 to 2023, incident cases of meningitis in the WPR declined from 638.02 thousand (95% uncertainty interval [UI], 497.54-789.94) to 162.67 thousand (136.19-192.51), and deaths declined from 78.16 thousand (55.76-103.50) to 15.17 thousand (11.45-21.03), although marked between-country disparities persisted. Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae accounted for the greatest number of meningitis-related deaths, although their burden declined over time. Haemophilus influenzae type b (Hib3) introduction was associated with a 31.85% reduction in Haemophilus influenzae meningitis deaths across the WPR (95% CI, -39.40% to -23.35%), and pneumococcal conjugate (PCV3) introduction with an 11.53% reduction in Streptococcus pneumoniae meningitis deaths (95% CI, -21.20% to -0.68%). Under a counterfactual scenario of 95% vaccine coverage, Haemophilus influenzae meningitis deaths were projected to further decline by 14.82% (95% CI, 7.33%-21.41%), and Streptococcus pneumoniae meningitis deaths by 12.27% (2.43%-20.92%). Conclusions The burden of meningitis in the WPR declined substantially from 1990 to 2023, but persistent cross-country inequalities and shifts in age-specific and pathogen-specific patterns remained. Hib3 and PCV3 vaccine introductions were associated with meaningful reductions in vaccine-targeted meningitis mortality, though the effect varied across countries.