Global socioeconomic inequalities in vaccination coverage, supply, and confidence.

Sustainable Development Goal (SDG) adopted in 2015 aim to reduce inequalities and achieve universal health coverage, including access to essential vaccines for all. Using data from WHO, the Vaccine Confidence Project™, World Bank, and UNDP, we analyzed between-country inequalities in coverage of four vaccines (DTP1, DTP3, MCV1, and POL3), vaccine stock-outs, and vaccine confidence. Economic- and education-related inequalities in coverage (measured by the concentration index) declined from 2015 to 2019, increased in 2020, peaked in 2021, and have declined again since 2022. Inequalities increased continuously in the Region of the Americas. Over 2015-2022, 94 countries/territories reported at least one national level DTP-containing vaccine stock-out. Countries/territories with higher income or education attainment showed lower vaccine confidence. Our study underscores the decrease of inequalities in vaccination coverage following the SDG adoption in most regions, and emphasizes the need to address vaccine stock-outs and strength the vaccine confidence.