Work

At risk of reversal? Sustainability gaps in Big Catch Up (BCU) institutionalization: insights from multi-country assessments

Year: 2026

Type: preprint

Abstract: Background The Big Catch-Up (BCU) initiative was launched across 36 countries to mitigate COVID‑19–related declines in routine immunization and to reach zero-dose and under-immunized children. The initiative mobilized substantial resources, political commitment, and technical support within a defined timeframe. However, emerging evidence indicates that progress remains uneven and vulnerable to reversal. As countries move from this time-bound intervention toward sustained routine catch-up delivery, institutionalizing BCU strategies and achievements within national health systems has become critical. To support this transition, BCU Alliance partners developed the Catch-Up Institutionalization Assessment Tool (CU-IAT), designed to help countries assess progress and readiness for embedding catch-up vaccination into routine systems Methods This paper employed established frameworks such as WHO Health Systems Building Blocks to conduct a structured qualitative thematic analysis of CU-IAT submissions from 16 BCU countries. The analysis examined institutionalization progress across eight health system domains and applied cross-country descriptive methods to identify common patterns, gaps, and sustainability risks. Results Findings show operational institutionalization of catch-up vaccination is well advanced. Thirteen countries updated policies, 14 integrated catch-up into routine service delivery through strengthened microplanning and outreach, and 15 institutionalized health worker capacity and reporting systems. However, long-term system enablers remain limited: only two countries reported sustained financing, six integrated vaccine forecasting and supply planning, and eight institutionalized long-ter technical assistance. Persistent gaps, reliance on partner support, and uneven workforce and data system capacity created varying levels of sustainability readiness, raising concerns about possible reversal of BCU gains as external support phases out. To address these risks, the paper proposes a Sustainability Transition Framework (STF) to classify readiness, identify residual risks, and prioritize transition actions. Strengthening financing, supply planning, technical capacities, and government ownership is essential to consolidate gains and sustain resilient, equitable immunization aligned with IA2030 goals. Conclusion The Big Catch-Up demonstrated that catch-up vaccination can be embedded within routine immunization systems, but sustaining gains requires institutionalizing not only practices but also financing, governance, and health system functions. Stronger government ownership, domestic resource mobilization, and continued partner support are essential to ensure long-term resilience and equity, consolidating progress and aligning with IA2030 goals.

Source: Research Square

DOI: 10.21203/rs.3.rs-11077439/v1