Abstract
BACKGROUND: Childhood vaccination rates in Yemen remain alarmingly low, and recent political developments have restricted vaccine delivery. Understanding population access to vaccinations through existing delivery modalities, including fixed and mobile services, is critical to inform strategies to improve access, increase coverage, and prevent outbreaks. METHODS: We developed a geospatial model of national and subnational vaccination access via fixed health facilities and mobile health teams, using newly developed datasets accounting for conflict-related effects. We calculated travel times to fixed health facilities and mobile sites offering immunizations and estimated the number and percentage of the under-5 population with access to vaccines. We also conducted a scale-up model to identify and prioritize locations where additional mobile teams would most improve vaccination access. RESULTS: We estimate that in 2023, 66.3% (3.57 million) of the Yemeni under-5 population lived within a 30-minute walk of a health facility or mobile site offering vaccinations, compared to 56.5% living within a 30-minute walk of a health facility alone. Even with mobile contributions, we find substantial regional variation; in 13 of 22 governorates, more than one-third of children cannot access a vaccination site within 30 min. In our scale-up analysis, we identify optimal locations for 300 new mobile sites that would increase access by an additional 7.2% of the population. CONCLUSIONS: Using mobile teams improves geographic access to vaccinations in Yemen; however, significant access gaps will remain even with dedicated scale-up efforts. Geospatial modelling offers a rigorous approach to evaluating the impact of different service delivery methods in conflict settings and can help optimize targeting strategies.