Determinants of Complete Childhood Immunization in Rural Communities of Rivers State, Nigeria: A Randomized Controlled Study

Abstract

Background: Incomplete childhood immunization remains a major public health challenge in rural Nigeria, driven by both caregiver- and health system-related factors. This study assessed the determinants of complete childhood immunization using a community volunteer-driven intervention in rural communities of Rivers State. Methods: A parallel-group randomized controlled trial was conducted among 368 caregivers of infants aged 0–6 weeks in Emohua and Etche Local Government Areas. Participants were randomly assigned to intervention (n=184) and control (n=184) groups. The intervention group received structured immunization education delivered by trained community volunteers, while the control group received routine care. The primary outcome was complete immunization assessed when the child was expected to receive the 3rd dose of the Pentavalent vaccine at the age of nine months. Data were analyzed using intention-to-treat principles, with logistic regression used to identify independent predictors. Results: A total of 339 participants completed the study (intervention: 173; control: 166). Complete immunization coverage was significantly higher in the intervention group (69.9%) compared with the control group (46.4%) (p<0.001), representing a 23.5% absolute increase. Children in the intervention group were more likely to be fully immunized (RR=1.51; NNT≈5). Independent predictors of complete immunization included exposure to the intervention (AOR=2.69, 95% CI: 1.72–4.20), good knowledge of the immunization schedule (AOR=2.41, 95% CI: 1.43–4.05), perceived benefits of immunization (AOR=1.88, 95% CI: 1.16–3.05), paternal education and women’s autonomy (AOR=2.17, 95% CI: 1.21–3.25), and favorable health system factors (AOR=2.35, 95% CI: 1.36–3.14). The model demonstrated acceptable predictive performance (AUC=0.76; accuracy=72.6%). Conclusion: Community volunteer-driven education significantly improves childhood immunization uptake in rural settings. Addressing caregiver knowledge, household dynamics, and health system barriers is essential for achieving optimal immunization coverage.