Explanatory Factors of Vaccination Dropout Among Children Aged 12–23 Months in Kikula Health Zone, DRC (Preprint)

BACKGROUND Vaccination remains one of the most cost-effective public health interventions to prevent childhood morbidity and mortality. Despite the efforts of the Expanded Program on Immunization (EPI) in the Democratic Republic of Congo (DRC), full immunization coverage among children aged 12–23 months remains critically low, particularly in the Kikula Health Zone. Recent data indicate a concerning dropout rate, with nearly 40% of children failing to complete their vaccination schedule. This phenomenon undermines national health objectives and increases vulnerability to vaccine-preventable diseases such as measles, polio, and tuberculosis. Understanding the underlying causes of vaccination abandonment is essential to designing targeted interventions that can improve coverage and equity in immunization services. OBJECTIVE This study aimed to identify the key explanatory factors associated with vaccination dropout among children aged 12 to 23 months in the Kikula Health Zone, Democratic Republic of Congo. Specifically, it sought to assess the influence of sociodemographic characteristics, parental knowledge, perceptions of vaccination services, and organizational barriers on immunization completion rates. METHODS A cross-sectional analytical study was conducted from April 22 to May 22, 2025, in the Kikula Health Zone, Haut-Katanga province, Democratic Republic of Congo. A three-stage cluster sampling technique was used to recruit 300 mothers or guardians of children aged 12–23 months. Data were collected using a structured questionnaire administered via KoboCollect and analyzed with SPSS version 25.0. Chi-square tests and logistic regression were applied to identify factors significantly associated with vaccination dropout. Ethical approval was obtained, and informed consent was secured from all participants. RESULTS Among the 300 children surveyed, only 61.67% had completed their vaccination schedule. The analysis revealed that the absence of a vaccination card (adjusted OR = 30.89; 95% CI: 11.64–81.97; P < .001) and poor maternal knowledge of vaccine-preventable diseases (adjusted OR = 29.62; 95% CI: 1.29–680.31; P = .034) were significantly associated with vaccination dropout. Other factors such as maternal age, education level, fear of side effects, and short duration of residence were significant in bivariate analysis but not in multivariate models. CONCLUSIONS Vaccination dropout among children aged 12–23 months in the Kikula Health Zone is driven primarily by the absence of vaccination documentation and poor maternal knowledge of vaccine-preventable diseases. These findings underscore the need for targeted interventions focused on improving health education, ensuring consistent availability of vaccination cards, and strengthening community engagement. Addressing these barriers could significantly enhance immunization coverage and reduce the risk of preventable childhood illnesses in similar urban-rural Congolese settings