Trends and cross-county disparities in childhood pneumococcal vaccination in Zhejiang Province, China, 2011–2022

BACKGROUND: Pediatric pneumococcal conjugate vaccine (PCV) and pneumococcal polysaccharide vaccine (PPV23) remain voluntary and out-of-pocket in China, and long-term evidence on market transition and socioeconomic disparities is limited. METHODS: We analyzed vaccination registry data for 2011-2022 birth cohorts across 90 counties in Zhejiang Province, stratified into four Gross Domestic Product (GDP) strata. Descriptive analysis and mapping were combined with a permutation-based transition-year analysis to assess the socioeconomic gradient in the PPV23-to-PCV crossover. Segmented beta-binomial mixed-effects regression models estimated period-specific annual odds ratios (ORs) across vaccine supply periods, accounting for county- and city-level clustering. RESULTS: Among 9,699,424 children, coverage for ≥ 1 dose of PCV and PPV23 was 13.5% and 25.7%, respectively. From 2011 to 2022, PCV coverage increased from 0.9% to 48.4%, whereas PPV23 declined from its 2017 peak of 33.7% to 6.3%. The PPV23-to-PCV crossover occurred earlier in higher-GDP counties, showing an ordered socioeconomic gradient (Kruskal-Wallis H = 46.12, permutation P for trend < 0.0001). Segmented models showed substantial local clustering (county-level intraclass correlation coefficient = 0.508). During 2017-2019, annual odds of PCV13 uptake increased nearly three-fold across GDP strata, while PPV23 declined. During 2020-2022, domestic PCV13 expansion produced a parallel increase across strata (annual ORs: 1.38-1.43, P < 0.001), preserving relative economic disparities; meanwhile, accelerated PPV23 decline (annual ORs: 0.53-0.57, P < 0.001) narrowed absolute PPV23 coverage differences by 2022. CONCLUSIONS: China's pneumococcal vaccine market transition reshaped vaccination equity. Domestic PCV13 expansion increased uptake but did not eliminate socioeconomic disparities. Stronger provider recommendation, targeted affordability measures, and progress toward National Immunization Program inclusion are needed to achieve equitable protection.