Regional Inequities in Childhood Vaccination Coverage in Brazil: A Multivariate Ecological Analysis With a Spatial and Socioeconomic Focus

Abstract

Introduction: Childhood immunization currently poses a significant challenge in terms of epidemiological surveillance and coverage, with multiple factors contributing to suboptimal uptake or the attrition of vaccination data. Objective: To evaluate the trends in childhood vaccine coverage in Brazil from 2018 to 2022 and analyze its association with socioeconomic and macrosocial indicators, as well as spatial patterns of inequality, accounting for the heterogeneous impacts of the COVID-19 pandemic. Method: An ecological and analytical study was conducted utilizing data from the National Immunization Program Information System (SI-PNI) and IBGE indicators concerning the population aged 0 to 14 years. The methodological framework integrated multivariate statistical analysis—including multiple linear regression and Spearman correlations—with spatial modeling at the state level (Federative Units). This strategy facilitated the identification of territorial vulnerability clusters and the isolation of social determinants associated with coverage oscillations. Results: The analysis of 432.7 million doses revealed a sharp decline between 2019 and 2021, with only a partial recovery in 2022. Critical fragility was observed in multi-dose vaccine regimens (Rotavirus and Tetravalent), alongside severe regional disparities that established the North and Northeast regions as vulnerability hubs. The Gini Index emerged as the most robust predictor of vaccine coverage, outweighing geographic and urbanization variables, demonstrating that income inequality is a primary determinant of immunization access levels. Conclusions: The sustainability of childhood immunization is contingent upon addressing socioeconomic inequalities. This necessitates territorialized public policies, active surveillance (active search), and social disparity-sensitive financing to mitigate the risk of reemerging vaccine-preventable diseases.