JMIR Publications

ABSTRACT

Background:

Vaccination is among the most effective public health interventions to reduce childhood morbidity and mortality. Despite WHO recommendations, global immunization coverage has declined in recent years, with the COVID‑19 pandemic causing the largest sustained backslide in routine immunization in three decades. In the Democratic Republic of Congo (DRC), full immunization coverage remains below 50%, hindered by inequities, stockouts, and financing delays. In the Kikula Health Zone, administrative reports suggest coverage exceeding 100%, yet independent surveys consistently reveal low completion rates and high dropout between BCG and measles vaccines. No prior study has specifically examined determinants of dropout in this setting.

Objective:

This study assessed the prevalence and determinants of vaccination dropout between BCG and measles vaccines among children aged 12–23 months in the Kikula Health Zone, Likasi, DRC. We hypothesized that maternal sociodemographic characteristics, knowledge of immunization, perceptions of services, and health‑system factors are associated with dropout risk.

Methods:

An analytical cross‑sectional survey was conducted from April 22 to May 22, 2025, using three‑stage cluster sampling to recruit 300 mother–child pairs. Vaccination status was verified using cards; children without documentation were excluded to minimize misclassification. Structured questionnaires captured sociodemographic data, child characteristics, maternal knowledge, perceptions of services, and health‑system access. Dropout was defined as receipt of BCG but not measles vaccine. Bivariate associations were tested using chi‑square, and multivariate logistic regression identified independent predictors, with robust standard errors to account for clustering. Ethical approval was obtained from the University of Kinshasa School of Public Health.

Results:

Among 300 children, 115 (38.3%) had dropped out between BCG and measles vaccination, while 185 (61.7%) completed the schedule. Possession of a vaccination card was the strongest predictor: children without a card had 30‑fold higher odds of dropout (AOR 30.9, 95% CI 11.6–82.0, p < .001). Other factors associated with dropout in bivariate analysis included shorter residence duration (≤5 years), lower maternal education, and non‑use of child health services, though these lost significance in multivariate models. Maternal knowledge gaps were notable: 169/300 (56.3%) did not know their child’s vaccination status, and 148/300 (49.3%) expressed fear of side effects. Service perceptions were generally positive (294/300, 98% reported good reception), but 108/300 (36%) experienced waiting times of 1–2 hours. Exclusion of undocumented children likely led to underestimation of dropout prevalence.

Conclusions:

Vaccination dropout between BCG and measles remains high in the Kikula Health Zone, driven primarily by lack of vaccination cards and maternal knowledge gaps. Administrative coverage data (>100%) mask substantial dropout, underscoring the need for improved documentation, maternal education, and targeted outreach. Programmatic implications include strengthening card management, deploying mobile vaccination units, and enhancing community reminders. Findings highlight the importance of addressing both demand‑ and supply‑side barriers to reduce dropout and improve equity in immunization coverage in the DRC