Prevalence and its associated factors of zero-dose vaccination and barriers among children under the age of 2 years in Southwest Ethiopia: A mixed-method study

Introduction: Vaccination significantly reduces morbidity and mortality among children from vaccine-preventable diseases. Despite a global and regional immunization coverage estimate of 74%, Ethiopia has ~1,146,000 zero-dose children. Therefore, this study estimated the prevalence of zero-dose vaccination and identified factors and barriers among children under 2 years of age in South West Ethiopia. Method: An explanatory sequential mixed-methods design was employed; the quantitative component consisted of a community-based cross-sectional study, and the qualitative component was assessed using a qualitative descriptive approach through in-depth interviews. Following data cleansing, the status of the first dose of the pentavalent vaccination was classified as either “vaccinated for first dose of the pentavalent vaccine” or “not vaccinated for first dose of the pentavalent vaccine.” Then, associated factors of being zero-dose at p < 0.05 were identified using logistic regression analysis. Subsequently, reflexive thematic analysis was employed for qualitative data analysis because it enables both interpretive developments of latent meanings underlying barriers to zero-dose vaccination and inductive coding based on participant narratives. Result: The results indicated that 17% of children were zero-dose, and lack of antenatal care visit (adjusted odds ratio = 4.005; 95% confidence interval: 2.011–7.975, p = 0.000), lack of information regarding immunization services (adjusted odds ratio = 2.493; 95% confidence interval: 1.293–4.809, p = 0.006), and maternal gravidity of ⩽3 (adjusted odds ratio = 4.198; 95% confidence interval: 1.425–12.370, p = 0.009) were significant factors for zero-dose vaccination. From the majority of in-depth interview participants’ expressions, myths and misinformation about vaccination, far distance from the health facility, and lack of convenient means of transport were important barriers for childhood vaccination. Conclusion and recommendation: This study revealed that the magnitude of zero-dose children is 17%, and demonstrated that zero-dose vaccination in Southwest Ethiopia is best understood through a multi-level ecological lens. While quantitative analysis identified antenatal care attendance, maternal knowledge/information, and gravidity as significant predictors, qualitative findings revealed how individual knowledge gaps, interpersonal influences, institutional service limitations, and broader structural barriers in underserved agrarian and pastoralist settings intersect to shape immunization behavior.