Risk factors associated with zero-dose and under-immunized children, and the number of vaccination doses received by children in Ethiopia: a negative binomial regression analysis.

Introduction: Despite the proven effectiveness of vaccination in improving child health and well-being, millions of children remain unvaccinated globally. Ethiopia has increased child vaccination coverage by threefold in the last decades. However, it is one of the top contributors to zero-dose and unimmunized children in Africa. Thus, we examined risk factors associated with zero-dose, under-immunization, and the number of vaccination doses received by children in Ethiopia.

Methods: A cross-sectional household survey was conducted as part of the formative assessment for the Strengthening Service Delivery (SSD) project from July to August 2024. A stratified two-stage sampling was employed to recruit 1,368 mothers of children aged 12-23 months from agrarian and pastoral regions of Ethiopia. A multilevel negative binomial model was then fitted to estimate associations between individual- and community-level independent variables and the number of vaccine doses received. Adjusted incidence rate ratios (AIRR) with 95% CI were reported to declare the associations.

Results: About 14% of children did not receive any vaccinations, and 62% were under-immunized, with significant regional disparities: 9% of children in agrarian regions versus 69% in the pastoral areas received no vaccinations, while 60% of children in agrarian regions were under-immunized compared to 92% in the pastoral areas. Mothers attended higher education (AIRR = 1.20; 95% CI [1.01-1.42]), household wealth status of rich (AIRR = 1.39; 95% CI: [1.16-1.67]) and middle class (AIRR = 1.32; 95% CI: [1.09-1.61]), previous history of facility delivery (AIRR = 1.57; 95% CI: [1.35-1.83]) and home visit by community health workers (CHW) during pregnancy (AIRR = 1.32; 95% CI: [1.15-1.52]) and having any under 5 children with vaccination card (AIRR = 2.45; 95% CI: [2.08-2.90]) increased the likelihood of receiving vaccinations. However, children from the pastoral region (AIRR = 0.40; 95% CI: [0.29-0.54]) were less likely to receive higher vaccination doses.

Conclusion: Our study highlighted individual and community-level factors associated with the number of vaccination doses children received in Ethiopia. To address zero-dose and under-immunized children in Ethiopia, contextualized intervention focusing on the pastoral and vulnerable population is needed. Moreover, strengthening the health system and expanding healthcare access in the underserved population could help improve child vaccination.