OBJECTIVES: this study aims to determine the extent of immunization coverage among children in low and middle-income countries, as well as to fill in the gaps in awareness about system-level obstacles that currently hinder the effective delivery and uptake of immunization services through EPI.

METHODS: This study was conducted by using a systematic literature review by following PRISMA guidelines. The electronic databases were used PubMed and Google Scholar along with targeted grey literature. The search techniques for electronic databases used both Medical Subject Headings (Mesh) and free-text words were tailored to each database's specific needs using controlled vocabulary that was limited to the English language from 2000 and 2020.

Of 689 records, eleven articles were included in this review met the inclusion criteria. the quality of included studies was evaluated by following JBI’s checklist and extracted into tables created by one investigator and double-checked by another.

RESULTS: In total, five articles related to vaccination coverage, 4 studies on components of the routine immunization system, one article on implementation of new and under-utilized vaccines and one were on vaccines financing. Review findings suggest that specific strategies to reduce inequality may be required. Vaccine procurement and pricing strategies, as well as vaccine customization to meet the needs of low- and middle-income countries, are all critical components in strengthening immunization systems.

CONCLUSIONS: The current findings could be used to establish practical strategies for countries and development partners to address coverage gaps and improves vaccination system effectiveness.