49 Policy and practice in the delivery of catch-up and life-course vaccination in low- and middle-income countries (LMICs) for adolescents and adults: a systematic review and policy analysis

Abstract PTH 6: Health Policy and Health Services 1, B307 (FCSH), September 4, 2025, 16:30 - 17:30 Aims Catch-up vaccination is vital in low- and middle-income countries (LMICs) to improve immunisation coverage across the lifespan for migrants, and marginalized populations who may have missed routine vaccines as children. The WHO’s big catch-up initiative aims to recover immunisation rates post-COVID-19, prioritising zero-dose children, however, evidence on catch-up strategies in LMICs, particularly for older groups, remains limited. This study evaluates interventions, policies, and best practices in catch-up vaccination in LMICs. Methods A systematic review of studies from 2000–2024 examined catch-up vaccination policies, strategies, and interventions for adolescents (12–18 years) and adults (19–65 years) across 124 LMICs following PRISMA guidelines. Research was sourced from five academic databases (Embase, MEDLINE, PsycINFO, Global Health, Web of Science) and grey literature (including WHO, Ministry of Health websites) in any language. Primary outcomes assessed policy implementation, intervention strategies, and barriers, while secondary outcomes identified facilitators and best practices for reaching underserved populations. Results From 7,820 studies screened, 310 were included, covering successful catch-up interventions for measles, polio, cholera, HPV, and COVID-19 vaccination in Nigeria, Brazil, Morocco, India, Uganda, and Ethiopia. Strategies used to support catch-up included mobile clinics, school-based vaccination, SMS reminders, and culturally tailored outreach. Barriers include low awareness, financial constraints, and health system limitations. Of the 124 LMICs included, 84 had a national catch-up vaccination policy, but only 16 explicitly included migrants and refugees. Within these the focus was on children. In the MENA region there is a need for more inclusive policies at the national level to remove financial and legal obstacles to vaccination for migrant populations. Conclusions Expanding catch-up vaccination programmes for measles, polio, and other preventable diseases is essential to closing immunity gaps, aligning with key global priorities to ensure equitable access for refugees and migrants.