Monitoring the SDG immunization indicator: Approaches and challenges

The operational definition of the Sustainable Development Goal (SDG) immunization indicator encompasses coverage with full courses of diphtheria-tetanus-pertussis (DPT3), pneumococcal (PCV3), measles (MCV2), and human papillomavirus (HPV) vaccines. We assessed the feasibility of using publicly available national survey data to measure this using a summary co-coverage indicator. Due to lack of data on adolescent HPV vaccine coverage, HPV was excluded from the indicator. While 88 national surveys provided data on child immunizations since 2015, only 33 were suitable for calculating co-coverage-the receipt of all three child vaccines (DPT3, PCV3, and MCV2) by 36 months of age. Co-coverage ranged widely from 6.1 % in Ethiopia to 90.2 % in Rwanda. Because co-coverage requires that children receive all three vaccines, its median level of 60.2 % was 16 percentage points lower than the median for the country-specific average of the same vaccines. Socioeconomic and urban-rural inequalities in co-coverage were observed in most countries, with wider inequalities associated with co-coverage than average coverage. Ecological analyses revealed a strong correlation between co-coverage and existing summary measures based on WHO and UNICEF estimates. These findings show a critical need for more frequent and comprehensive national surveys, particularly for adolescent populations, to enable accurate monitoring of immunization along the life-course as intended by the SDG framework. Given current funding constraints for population-based surveys, reliance on administrative data for coverage monitoring is likely to continue.