Subnational implementation review workshop of the Big Catch-Up (BCU) immunization initiative in priority countries of the WHO South-East Asia Region
10–12 December 2025, New Delhi, India
Overview
The WHO Regional Office for South-East Asia (WHO-SEARO) convened the subnational implementation review workshop of the Big Catch-Up (BCU) immunization initiative in New Delhi on 10–12 December 2025, bringing together national and subnational immunization managers, technical experts and WHO staff members from Nepal, Myanmar, India and Timor-Leste, alongside WHO personnel from the Regional Office and headquarters. Key partners – including the United Nations Children’s Fund (UNICEF), Gavi, the Vaccine Alliance (Gavi), Program for Appropriate Technology in Health (PATH), John Snow India (JSI) and Immunization Technical Support Unit (ITSU) – joined the workshop to jointly review BCU progress and shape strategies for institutionalizing catch-up vaccination.
The workshop highlighted significant recovery since the launch of the BCU initiative in 2023 to address immunity gaps widened by COVID-19. Countries reported meaningful reductions in zero-dose children, improved antigen coverage and increasing integration of catch-up into routine systems. India’s progress stood out, with a 43% reduction in zero-dose children and strong antigen-specific gains supported by digital platforms such as the Universal Immunization Web‑enabled Network (U-WIN).
Throughout the workshop, country teams exchanged lessons on addressing persistent routine immunization gaps, leveraging digital tools for tracking and monitoring, and tailoring strategies for urban, mobile and hard-to-reach populations. Field visits in Delhi provided participants with practical exposure to service delivery models, community engagement approaches and local innovations that are helping to strengthen coverage.
Technical sessions from WHO and partners reinforced these discussions. WHO emphasized critical data gaps and the need for stronger digital systems to sustain routine catch-up. The WHO headquarters (WHO HQ) provided global insights, noting that while the BCU initiative improved planning, monitoring and stakeholder engagement, countries must now transition from campaign-style activities to fully institutionalized routine systems.
Partners presented complementary perspectives. Gavi outlined its 6.0 strategy to streamline funding, improve data systems and scale innovations. UNICEF presented regional insights and case studies from Nepal and Myanmar, underscoring the role of community engagement, behavioural insights, and strengthened cold-chain and delivery systems in improving equity and sustaining routine immunization.
India’s Delhi team demonstrated how targeted microplanning, U-WIN-enabled tracking and focused outreach helped reduce zero-dose children in complex urban settings. PATH showcased a range of innovations – from cold-chain technologies to 5 human-centered design and digital tools – that can improve access for underserved populations. ITSU highlighted the need for stronger urban-focused planning, enhanced microplanning and data-driven, community-centered delivery approaches. The JSI emphasized the importance of localization through community-based organizations and hyper-local communication to improve vaccination uptake and equity.
Despite progress, participants acknowledged ongoing challenges, including coverage inequities, data quality issues, resource constraints and workforce limitations. Countries identified key priorities: developing country-owned workplans, strengthening real-time data systems, sustaining partner engagement, and prioritizing approaches for vulnerable and underserved populations.
