Understanding Barriers and Facilitators Influencing Immunization Coverage in Low-Income Settings: A Global Systematic Perspective

Immunization is a cornerstone of global health, yet low-income countries continue to face persistent gaps in vaccine coverage due to complex social, economic, and systemic challenges. This review offers a global systematic perspective on the barriers and facilitators influencing immunization uptake in resource-constrained settings. Drawing on theoretical frameworks such as the Social Ecological Model and WHO’s Health System Building Blocks, it synthesizes evidence across regions to highlight key determinants. Barriers include misinformation, cultural beliefs, gender norms, financial hardship, weak health infrastructure, stockouts, and governance limitations. Geographic isolation, conflict, and disruptions caused by the COVID-19 pandemic further exacerbate inequities. Conversely, facilitators such as community engagement, trained health workers, technological innovations, donor support, and integrated primary health care strengthen immunization performance. Case studies from Rwanda, Bangladesh, and Ethiopia demonstrate how local ownership, decentralized governance, and social mobilization can achieve high coverage despite resource constraints. Policy implications emphasize the need for equity-focused approaches, sustainable financing, cross-sector collaboration, and strengthened data systems. Addressing research gaps—including intersectional barriers and evolving behavioral dynamics—is essential for designing responsive interventions. Ultimately, equitable immunization coverage requires resilient health systems, empowered communities, and context-sensitive strategies that advance global health security and long-term public health resilience. .