Zero-dose Children in Timor-leste: Household-level Risk Factors and Implications for the Immunization Agenda 2030

Objectives To estimate the prevalence of zero-dose children in Timor-Leste (2022–2023), identify household-level risk factors, and assess progress toward Immunization Agenda 2030 (IA2030) targets. Methods This retrospective cohort study analyzed national immunization data from the Timor-Leste EPI Factsheet 2024 and WHO/UNICEF Estimates of National Immunization Coverage 2023. Zero-dose children were defined according to the IA2030 standards (no first dose of DTP-containing vaccine). The primary outcome was the zero-dose prevalence in the 2023 birth cohort. Indicators corresponding to risk factors from a multi-country analysis of 82 low- and middle-income countries were extracted and descriptively compared with global estimates from the Global Burden of Disease Study 2023. This study adhered to the STROBE guidelines for observational research. Results In 2023, Timor-Leste had 33,260 live births and 3254 zero-dose children (9.8% of the birth cohort), a 22% reduction from 4184 (13.1%) in 2022. Neonatal tetanus protection improved to 85% (from 83%), with 15% unprotected—a group with three times the odds of being zero-dose (OR 3.00; 95% CI: 2.72–3.30). Skilled birth attendance was 57%, with 43% home deliveries—a group with nearly twice the odds of being zero-dose (OR 1.87; 95% CI: 1.70–2.05). All 14 districts (100%) now have updated micro-plans; zero districts show a > 10% DTP1-to-DTP3 dropout rate, a complete elimination from five districts (38%) in 2022. The number of districts achieving > 90% MCV1 coverage increased from five (38%) to ten (71%). The pneumococcal conjugate vaccine was introduced in January 2023. Conclusions Timor-Leste's 22% zero-dose reduction demonstrates that targeted microplanning and district accountability are effective strategies for addressing zero-dose children. However, the prevalence of 9.8% exceeds the global average, with access to maternal healthcare remaining the predominant risk factor. Achieving IA2030s 50% reduction target requires integrating maternal-child health services with immunization programs and reaching 43% of families delivering at home. These findings generate hypotheses for future prospective studies on integrated service delivery models in Southeast Asia.