A systematic review of barriers associated with immunization activities among under-5 children in Nigeria

Childhood immunization is a critical public health strategy for reducing vaccine-preventable diseases and associated mortality in Nigeria. Despite efforts to improve vaccination coverage, significant barriers persist, hindering the achievement of universal immunization. This study aims to comprehensively review the knowledge, practices, and factors influencing caregivers’ roles in childhood immunization in Nigeria. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PubMed, EMBASE, and African Journals Online were searched for studies published from January 2014 to June 2024 examining factors influencing childhood immunization in Nigeria. Qualitative, quantitative, and mixed-methods studies published in English were included, while non-peer-reviewed articles, reviews, letters, and studies not addressing vaccination knowledge, attitudes, and practices were excluded. Eligible studies were critically appraised using the Joanna Briggs Institute (JBI) tools. Data on study characteristics and vaccination-related findings were extracted and narratively synthesized to identify common themes and patterns. Following screening and eligibility assessment, 21 articles met the inclusion criteria and were included in the review. The included studies encompassed a range of cross-sectional and qualitative research, with a combined total of 29,321 participants. Five major themes emerged as barriers to childhood immunization in Nigeria: knowledge and awareness, characterized by inadequate knowledge, misinformation, fear, and communication gaps; access and availability, constrained by geographical and service barriers and competing caregiver demands; attitudes and beliefs, including safety concerns, mistrust, and traditional and religious beliefs; healthcare system factors, including workforce, training, infrastructure, and resource constraints; and sociodemographic factors, particularly education, income, gender, age, and language, which influenced immunization access and uptake. In our review, several critical barriers influencing childhood immunization in Nigeria were identified. Addressing these barriers required a multifaceted approach involving improved health literacy, enhanced healthcare infrastructure, culturally competent care, and targeted interventions to increase access and reduce disparities. Strengthening communication strategies and leveraging mobile technology for reminders could have significantly enhanced vaccination coverage. Policymakers and healthcare providers needed to prioritize these strategies to achieve higher immunization rates and improve child health outcomes in Nigeria. The protocol for this systematic review was registered with PROSPERO under registration number CRD42024558533.