Rapid convenience monitoring as a method to assess immunization status and programmatic reach across different age groups during the Big Catch-up: Experiences from 8 countries

Abstract Background Rapid convenience monitoring of immunization (RCM) is a field-oriented monitoring approach, derived from lot quality assurance sampling, designed to generate rapid, actionable local data for course correction and immunization programme improvement. This analysis summarizes experiences from eight countries that conducted RCM as part of the Big Catch-up immunization activities. The Big Catch-up was an initiative to provide vaccines missed following disruptions and backsliding in childhood vaccination coverage associated with the COVID-19 pandemic and persistent challenges. Methods The analysis summarizes experiences with RCM from Burkina Faso, Cameroon, the Democratic Republic of Congo, Guinea, the Gambia, Mali, South Sudan, and Tajikistan. Results Across settings, RCM was used by immunization programmes as a rapid operational tool to assess immunization status, identify missed children following catch-up vaccination activities, understand barriers and reasons for missed doses, and prompt programmatic action. Seven countries checked the vaccination status for children above 2 years of age, typically up to 5 years, with two countries checking up to 6 years of age; one country checked up to 2 years. Data collectors for RCMs were either independent groups or health workers assigned to neighboring areas to minimize bias. There was heterogeneity across core variables assessed by countries. DTP1 status among children > = 1 year, where assessed, was 83% in South Sudan to 99% in Tajikistan. The RCMs also identified persistent gaps of incomplete vaccination among eligible children, delays in vaccination according to national schedules, continued missed opportunities at service delivery points, and caregiver-facing barriers. Conclusions In all eight countries, RCMs led to immediate actions to catch up missed doses as well as programmatic recommendations to combine and integrate strategies to reach missed children. RCM can be a useful method to quickly obtain performance signals for childhood immunization and catch-up across age groups.