Reconstruction of immunisation during conflict: A mixed-methods cohort evaluation of programme delivery and outcomes in Myanmar

Introduction. Routine childhood immunisation is frequently disrupted in conflict-affected settings, leaving many children unvaccinated (zero-dose [ZD]). Their vaccination is now a global priority, but published evidence on restoring immunisation services in these settings is limited. We evaluated a nurse-led, community-based Expanded Programme on Immunisation adapted to a conflict-affected setting in Myanmar, focusing on factors associated with full immunisation (FI) among ZD children. Methods. This mixed-methods observational cohort study enrolled children from November 2023 to December 2025; analyses of FI outcomes were restricted to children enrolled >=18 months, with primary analyses focused on ZD children. Associations between programme delivery factors including vaccination opportunity (the ratio of vaccination sessions available to visits required for FI based on age and vaccination schedule [accelerated versus routine]) and FI were assessed using mixed-effects logistic regression with a random intercept for site. Programme cost and qualitative data from document review and questionnaires were also analysed. Results. Of 13,263 children enrolled, 6563 (49%) were in the analytic cohort; 2,684 (20%) were ZD. Among ZD, 452 (17%) were FI at 12 months and 1329 (50%) at 18 months. Accelerated schedule (OR 3.00, 95% CI 1.11-8.13) and greater vaccination opportunity (OR 2.1 per 0.5 unit increase in opportunity, 95% CI 1.8-2.4) were strongly associated with FI at 12 months, with smaller effects at 18 months. The cost per fully immunised ZD child was US$147, primarily reflecting substantial vaccine costs. Qualitative findings indicate that community engagement increased demand and access, but insecurity and logistical challenges limited service continuity and vaccination opportunities. Conclusion. FI improved over time but remained suboptimal through 18 months. Vaccination opportunity and schedule influenced the timing of FI, but sustained follow-up was critical for completion. Community-based delivery enabled restoration of immunisation services where formal systems had collapsed, demonstrating what is possible and what it demands in active conflict.