Childhood immunization barriers and interventions in low- and middle-income countries: A scoping review of access, delivery systems, and health literacy

Childhood immunization is among the most effective public health measures for preventing infectious diseases and reducing child mortality, yet coverage in many low- and middle-income countries (LMICs) remains suboptimal due to barriers in access, delivery systems, and caregiver acceptance. This scoping review mapped experimental and quasi-experimental studies from PubMed and Scopus (2000-2024) evaluating interventions to improve childhood immunization across three domains: access to services, distribution and logistics, and health literacy. Thirty-two studies met inclusion criteria. Community outreach, reminder/recall systems, and incentives improved vaccination uptake, timeliness, and completion. Supply-chain optimization and technology-assisted delivery enhanced vaccine availability and reduced stock-outs, especially in hard-to-reach settings. Educational and culturally tailored communication interventions strengthened caregiver knowledge and confidence. The findings demonstrate that coordinated strategies addressing both supply-side and demand-side constraints are most effective for achieving equitable and sustainable improvements in routine childhood immunization.