Routine immunization coverage and determinants among children aged 12–23 months in rural southeast Nigeria: evidence from a community-based study

Background Routine immunization is one of the most effective public health strategies for preventing vaccine-preventable diseases in children. Despite national immunization programs, coverage remains uneven in many rural areas of Nigeria. This study assessed routine immunization coverage and its determinants among children aged 12–23 months in Izzi Local Government Area, Ebonyi State, Nigeria. Methods A community-based cross-sectional study was conducted among caregivers of children aged 12–23 months. Using a cluster sampling technique, 501 caregivers were interviewed with a structured questionnaire. Data were analyzed using IBM SPSS version 20. Descriptive statistics summarized variables, while Chi-square tests and binary logistic regression identified factors associated with full immunization (p < 0.05). Results Overall, 75.4% of children were fully immunized. Coverage was highest for BCG (94.4%), OPV1 (95.8%), Penta1 (96.6%), and PCV1 (95.6%), but declined slightly for later doses including OPV3 (92.0%), measles (91.0%), and yellow fever (89.8%). Nearly all caregivers (99.4%) had heard of routine immunization, although detailed knowledge was limited. Transportation costs (72.3%) and vaccine unavailability (59.7%) were the most frequently reported barriers. Advice from health workers (76.6%) and availability of free vaccines (73.7%) were key facilitators. In multivariate analysis, caregiver occupation and religion were significant predictors of full immunization. Children of farmers were less likely to be fully immunized compared with those of civil servants (AOR = 0.47; 95% CI: 0.24–0.90; p = 0.023). Conclusion Routine immunization coverage in the study area remains below optimal levels. Strengthening health education and ensuring consistent vaccine availability may improve uptake in rural communities.