The “big six” countries of the World Health Organization South-East Asia Region (WHO SEAR) are currently facing severe challenges in measles elimination and subsequent childhood mortality reduction, with inadequacies and inequalities in coverage of the measles-containing-vaccine first-dose (MCV1) being major obstacles. However, these concerns of disparities in MCV1 coverage have yet to be thoroughly investigated. Data from the most recent Demographic and Health Surveys, as well as Multiple Indicator Cluster Surveys, were utilised. Data were disaggregated by geographic region, as well as socioeconomic and nutritional aspects, to offer a full picture of existing MCV1 coverage gaps. Only nine of the 104 sub-national districts had met the WHO’s target of 95 percent MCV1 coverage. Geographic disparities were more prominent in nations with lower levels of coverage.

Inequalities were visible in all nations except Thailand, and they were more prominent in the categories of wealth, education, ANC status, and vitamin A supplementation (VAS) when compared to gender and urban/rural location. Wealth disparities in Bangladesh, education disparities in Indonesia, ANC disparities in Myanmar and Nepal, and VAS disparities in Indonesia and Myanmar were all notable. To enhance MCV1 coverage and minimise childhood mortality, equity-oriented improvements in policies concentrating on health promotion and integrated interventions among disadvantaged communities must be undertaken.