Intensifying Routine Immunization in Border Communities: Lessons from a Targeted Health Facility Strengthening Approach (2022–2025)

Background: Routine immunization (RI) remains a cornerstone of child survival; however, inequities persist in hard-to-reach populations, particularly in border communities characterized by weak health systems, geographic isolation, and population mobility. These settings contribute disproportionately to the burden of zero-dose and under-immunized children in Nigeria and similar low-resource contexts. This study describes the design, implementation, and early outcomes of a targeted RI intensification initiative aimed at strengthening health facility (HF) service delivery in underserved border areas. Methods: An implementation research approach was applied using a four-phase model: (i) mapping and assessment of health facilities, (ii) data-driven prioritization, (iii) costed HF-level microplanning, and (iv) implementation with continuous monitoring. A total of 477 HFs were identified, of which 371 were mapped and 349 confirmed operational. Service availability and readiness were assessed using standardized tools, and facilities were prioritized based on Pentavalent vaccine first dose (Penta 1) coverage and Penta 1–Penta 3 dropout rates. Tailored interventions were developed and implemented in 78 low-performing facilities, with ongoing supervision and adaptive management. Results: Baseline findings revealed significant service delivery gaps. 17% of operational HFs did not offer RI services, 42% lacked antenatal care, 55% did not provide delivery services, and 63% lacked nutrition services. Malaria services were comparatively more available (86%), while family planning services were absent in 42% of facilities. These gaps indicate weak integration of primary healthcare services and contribute to missed opportunities for vaccination and suboptimal immunization outcomes. Conclusion: The RI intensification initiative demonstrates that a structured, data-driven, and facility-centered approach can effectively identify and address immunization service gaps in border communities. Strengthening RI requires integrated primary healthcare delivery, local stakeholder engagement, and adaptive implementation strategies. This model provides a scalable framework for improving immunization equity and reaching zero-dose populations in complex and underserved settings, contributing to global immunization goals such as Immunization Agenda 2030. Keywords: Routine Immunization; Border Communities; Health Systems Strengthening; Zero-Dose Children; Primary Healthcare; Nigeria