Incomplete vaccination among children aged 12–35 months in West Arsi Zone, Ethiopia

BACKGROUND: Vaccine-preventable diseases remain significant contributors to illness and death among children. Globally, immunization stands out as one of the most effective and economical public health interventions. In the West Arsi zone, the results of the Rapid Convenient Survey (RCS) were inconsistent with the DHIS-2 report regarding the coverage of full vaccination. OBJECTIVE: To determine the proportion of incompletely vaccinated children aged 12-35 months and identify associated factors. METHODS: A community-based cross-sectional study was conducted in the West Arsi Zone from June 23 to August 17, 2023. A total of 1,316 children were selected using a multi-stage stratified random sampling technique. Data were collected through face-to-face interviews with mothers or caretakers and by reviewing immunization records, utilizing a structured questionnaire programmed in Open Data Kit (ODK). The data were cleaned and analyzed using Stata version 17. A binary logistic regression model was developed to identify associated factors. RESULTS: The prevalence of incomplete vaccination was 43.6% (95% CI: 40.9, 46.3) by recall and/or card review, and 36.8% (95% CI: 33.7-39.9) by card review only. OPV0 and MCV2 had the highest incompleteness. The main reasons reported for incompleteness were the unavailability of the vaccine/vaccinator and not knowing the need for the next dose. Incomplete vaccination was associated with accessibility of the kebele, availability of a refrigerator at the health post, residence of the respondent, age of the respondent, respondent's education level, child sex, child age, respondent's awareness of HEWs, respondent's knowledge about immunization, means of transport to the health facility, wealth index, and participation in the Productive Safety Net Program. CONCLUSIONS: The study revealed a high proportion of incomplete vaccination among children, with coverage varying across different vaccines. Major gaps were observed in OPV0 and MCV2. A wide range of socio-demographic, health system, and accessibility related factors were significantly associated with incomplete vaccination. Enhancing caretaker awareness, improving health facility readiness, and addressing social and cultural barriers could improve vaccine uptake.