Asian Journal of Immunology

Routine childhood immunization remains one of the most cost-effective public health interventions, yet Nigeria continues to experience substantial gaps in coverage, timeliness, and completion of recommended vaccine series. These gaps are not uniform: they cluster by geography, socioeconomic position, maternal education, service accessibility, and health system performance, and they are amplified by insecurity, mobility, and trust deficits. This review synthesizes evidence on routine immunization coverage and its determinants in Nigeria, focusing on multi-level drivers that shape vaccination initiation, continuation, and completion. We highlight consistent demand-side determinants such as caregiver education and empowerment, household wealth, health service utilization, and information exposure; supply-side determinants such as service readiness, health worker practices, vaccine logistics, and missed opportunities; and contextual determinants such as place of residence, subnational inequities, and conflict-related disruption. We further discuss the growing programmatic emphasis on “zero-dose” and under-immunized children, and summarize promising intervention directions including community-engaged delivery, facility-based quality improvement to reduce missed opportunities, and targeted demand-generation combined with reliable service availability. The review concludes that Nigeria’s coverage challenges are best understood as an interaction between household vulnerability and system reliability, mediated by local context. Sustainable gains require integrated strategies that strengthen primary health care delivery, improve data-driven microplanning, reduce dropout through continuity of care, and tailor approaches to high-risk geographies and populations.