Spatial accessibility analysis of vaccination units in Gansu Province, China (2025).

This study evaluated the spatial accessibility of vaccination units in Gansu Province, China, using the Two-Step Floating Catchment Area (2SFCA) method, with data collected as of December 2025. A total of 2,119 vaccination units registered as of December 2025 were included as supply points, with staff count as the supply capacity measure. Spatial accessibility was calculated for 14,243 urban residential points and 184,112 rural toponym points using a 5 km catchment radius. Accessibility levels were classified using the Jenks natural breaks method, and spatial equity was quantified using the Gini coefficient. In urban areas, the mean accessibility index was 0.20 (range: 0-84.43), with 98.93% of points classified as low accessibility; the Gini coefficient was 0.957. In rural areas, the mean accessibility index was 0.068 (range: 0-97.74), with 99.57% of points at low accessibility and 57.28% having zero accessibility; the Gini coefficient was 0.751. Vaccination services in Gansu Province exhibit extreme spatial inequality, with near-universal low accessibility in rural areas. Targeted interventions are urgently needed to address these disparities and ensure equitable immunization coverage.