Socioeconomic inequality in second-dose measles vaccination dropout among children aged 15-35 months in East Africa: A decomposition analysis of a recent Demographic Health Survey.

Despite the availability of effective vaccines, measles is still a serious public health issue globally, especially in Sub-Saharan Africa, where outbreaks persist. The second dose of measles-containing vaccine (MCV2), which is essential for building herd immunity and preventing outbreaks, is not being administered to millions of children. Little is known about disparities in MCV2 dropout related to socioeconomic. This study assessed these disparities and identified factors contributing to MCV2 dropout. We used the most recent Demographic and Health Surveys data (2015-2023) from eight East African countries using a cross-sectional design. A weighted sample of 23,085 children aged 15-35 months was included. Erreygers' concentration index (ECI) and Fairlie decomposition technique were used to examine wealth-based inequalities and urban-rural disparities in MCV2 dropout. Analyses were performed using STATA 17. The pooled MCV2 dropout proportion was 48.13% (95% CI: 47.48, 48.77), ranging from 7.72% in Rwanda to 82% in Ethiopia. The proportion was higher in rural (49.61%) than urban areas (43.82%) and among the poorest households (54.1%) compared with the richest (42.6%), indicating a significant pro-poor inequality (ECI = -0.0930, bootstrap SE = 0.0074). Primary and above maternal education explained the largest portion of disparities (57.71%) followed by having postnatal care visits (15.37%). MCV2 dropout remains high in East Africa, with significant wealth and urban-rural disparities mainly difference in maternal education and access to health care. Prioritizing maternal education, particularly in rural areas, and improvement to ANC, PNC, and institutional delivery services can reduce dropout through targeted caregiver education and remainder-based intervention.