Saadaq Adan Hussein, Marian Muse Osman, Mohamed Mohamoud Hassan, Yahye Sheikh Abdulle Hassan, Abdirahman Aden Hussein, Abdinur Hussein Mohamed, Rage Adem, Mohamed MAli Fuje, Khadar Hussein Mohamud, Ayan Nur Ali, Abdirahman Moallim Ibrahim, Ashraf Ali
BACKGROUND: The Immunization Agenda 2030 (IA2030), led by WHO and partners, targets the global challenge of zero-dose children, who face higher risks of vaccine-preventable diseases. Globally, 18 million children remain zero-dose, with over half in conflict or humanitarian settings. In Somalia, about 60% of children are zero-dose, and during the 2022-2024 drought, over 70,000 deaths occurred, with nearly 40% among children under five. This review explores the burden, determinants, and geographic distribution of zero-dose children in Somalia's conflict-affected regions. METHODS: This narrative review followed SANRA guidance. We searched PubMed, Scopus, Web of Science, Google Scholar, and key institutional sites (WHO, UNICEF, ReliefWeb, MoH Somalia, NGOs) for English-language literature (1990-July 31, 2025). From 197 records were identified, 82 new studies were included, resulting in a total of 279 studies after de-duplication and two-reviewer screening. Evidence was synthesized thematically and aligned to Immunization Agenda 2030 (IA2030) priorities. RESULTS: Zero-dose hotspots are concentrated in rural, nomadic, and conflict-affected zones, with Lower Juba reaching a peak of 62%. Key challenges include insecurity, limited access, disrupted supply chains, workforce shortages, and demand-side barriers like mistrust and misinformation. Humanitarian efforts are frequently hindered by checkpoints, blockades, and security concerns. From 2000 to 2024, Somalia's routine immunization program showed significant progress, with MCV-1 coverage rising from 50 to 71%, and MCV-2 from 5 to 55%, as per the WHO/UNICEF WUENIC data for the African region. CONCLUSION: Zero-dose children in inaccessible Somali districts are a pressing equity and health-security challenge. Sustaining recent national gains while fulfilling Immunization Agenda 2030 (IA2030)'s "leave no one behind" requires tailored outreach to remote communities, strengthened surveillance and e-registries for defaulter tracing, resilient cold-chain and WASH linkages, empowered community health workers (especially women), negotiated humanitarian access, and a progressive domestic co-financing roadmap alongside partner support.