Abstract Introduction Understanding structural and contextual factors behind COVID-19 vaccine uptake is essential for designing equitable immunization strategies. In Türkiye, a centrally coordinated campaign with notable regional variation offered an opportunity to explore how provincial characteristics influenced vaccine coverage. Methods This ecological study analyzes monthly full vaccination coverage (two doses) across 81 provinces and explores its association with 26 indicators grouped into six domains: health system capacity, healthcare utilization, population characteristics, economic indicators, urban environment, and socio-cultural factors. Domain-specific composite indices were created using standardized scores. Bivariate correlations and multiple linear regression models—adjusted for the proportion of the population aged 65 and older—were conducted. Results The proportion of the elderly population emerged as the most consistent predictor of vaccination uptake. Health system capacity was strongly associated with higher vaccination rates in the early months (β = 0.581 in February; β = 0.192 in March), emphasizing the role of public sector readiness. From March onward, healthcare utilization was a more stable determinant (β = 0.260 to 0.345), reflecting the importance of familiarity with and trust in health services. Socio-cultural factors—including education, women’s economic participation, and civic engagement—showed strong and sustained associations (β = 0.439 to 0.722). In contrast, population, economic, and urban environmental indicators showed weaker or inconsistent relationships. Conclusion Provinces with stronger public healthcare infrastructure and engaged communities achieved more equitable vaccine coverage. Türkiye’s experience underscores the importance of resilient, trusted primary care systems in driving immunization success. Future studies should investigate intra-provincial disparities to support more locally responsive public health strategies.
Etiler et al. (2026) studied this question.