Abstract
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.