Determinants of measles second dose vaccination dropout among children 24 - 35 months of age in Addis Ababa, Ethiopia. 2025: A Community based Unmatched Case-Control study.

BackgroundMeasles is a highly contagious infectious disease and a leading cause of childhood morbidity and mortality worldwide. In developing country like Ethiopia, effective immunization is a proven strategy for reducing measles related illness and deaths. However, measles second dose vaccination drop out has become a major public health concern. In a densely populated city such as Addis Ababa drop rate tends to be higher than the minimum acceptable threshold, leading to increased number of cases and recurrent outbreaks. Despite of this limited evidence exists on the determinants of second dose drop out and the problem is not well investigated, as a result this study will try to identify determinants of measles second dose vaccination dropout among children 24 - 35 months of age. ObjectivesTo identify determinants of measles second dose vaccination dropout among children 24 - 35 months of age Addis Ababa, Ethiopia in 2025. MethodCommunity based unmatched case control study was conducted in Addis Ababa from September 1/2024 to October /2025 with a total of 636 participants, consisting of 212 cases and 424 controls. Data were collected using structured Quesionariie and entered into EpiData 3.1 then StataSE 18 was used for detailed analysis including Descriptive statistics. Model fitness was checked using Hosmer-Lemeshow and multicollinearity were assessed using variance inflation factor. Furthermore, Bivariable and multivariable logistic regression analyses was employed and Adjusted odds ratio with 95% confidence intervals was used to identify significant variables. ResultsA total of 620 mothers/caregivers participants respond to the study, comprising 206 (97%) cases and 414(97.6%) controls, yielding a total response rate of 97.4%. In this study, waiting time longer than 30 minutes (AOR= 3.34, 95%CI: 1.86-5.9), Lack of counseling (AOR = 2.63, 95% CI: 1.60-4.30), Lack of reminders (AOR = 2.86, 95% CI: 1.89-4.30), Previous adverse event following immunization (AOR = 2.00, 95% CI: 1.39-3.00), postnatal care visit (AOR = 0.58, 95% CI: 0.40-0.85) and family size of greater than 3 (AOR = 1.96, 95% CI: 1.29-2.98) were significantly associated with measles second dose dropout. Conclusion and recommendationIn study shows measles second dose dropout is found to be associated with long waiting time, lack of counseling, lack of reminder, history of adverse event following immunization and postnatal visit. Which suggests Strengthening Immunization Counseling, reducing waiting time, establishing effective reminding system, integrating Immunization with postnatal services and promptly addressing concerns about adverse event following immunization can help reduce measles second dose dropout.