Exploring the landscape of routine immunization in Nigeria: A scoping review of barriers and facilitators.

Background: Despite global efforts to improve vaccination coverage, the number of zero-dose and under-immunized children has increased in Africa, particularly in Nigeria, which has over 2.1 million unvaccinated (zero dose) children, the highest in the continent. This scoping review systematically maps and summarizes existing literature on the barriers and facilitators of immunization in Nigeria, focusing on regional inequalities. Methods: A comprehensive search of electronic databases was conducted, encompassing all data from their inception to October 2023, to identify articles on the determinants of routine immunization uptake in Nigeria. Eligible studies were evaluated using predefined criteria, and the data were analyzed and visualized. Results: The results revealed distinct regional variations in factors influencing immunization practices across Nigeria's six geopolitical zones. Identified barriers include logistical issues, socio-economic factors, cultural influences, and systemic healthcare deficiencies. Key facilitators across multiple zones are health literacy, maternal education, and community leader influence. However, unique regional differences were also identified. In the North-East, significant factors included peer influence, robust reminder systems, provision of additional security, and financial incentives for health facilities. In the North-West, perceived vaccine benefits, fear of non-immunization consequences, urban residence, health literacy, and antenatal care visits were reported as crucial. Perceived benefits of vaccines and trust in healthcare providers were identified as predominant factors in the North-Central zone In the South-East, maternal autonomy, health literacy, and fear of non-immunization consequences were important. In the South-South, peer influence and reminder systems like WhatsApp and SMS were notable, alongside higher maternal education levels. The South-West highlighted maternal autonomy, peer influence, health card usage, high maternal education, and supportive government policies as critical factors. Conclusion: Our findings underscore the need for region-specific interventions that address these unique barriers to improve immunization coverage across Nigeria. Tailored approaches that consider the socio-economic, cultural, and logistical challenges specific to each region are essential to bridge the immunization gap.