Correlates of Zero-Dose Status among Children Aged 12-23 Months in the Luambo Health District, Democratic Republic of Congo: A Matched Case-Control Study

(1) Background: "Zero-dose" (ZD) refers to a child who has not received any doses of the pentavalent (diphtheria-tetanus-pertussis-Haemophilus influenzae type b (Hib)-hepatitis B) vaccine. ZD children are vulnerable to vaccine-preventable diseases (VPDs). Luambo health district (HD) is one of 26 HDs in Kasai Central Province in Democratic Republic of the Congo and had the largest number of ZD children in 2021. This study was conducted to identify factors associated with ZD status among children in Luambo HD. (2) Methods: We conducted a mixed-methods study of children aged 12-23 months in Luambo HD. (3) Results: A total of 445 children aged 12-23 months were included in the study, including 89 cases and 356 controls. Children who were born in Angola (AOR = 3.2; 95% CI = 1.1 to 9.8; p = 0.046), born at home (AOR = 5.2; 95% CI = 2.1 to 12.5; p < 0.001), whose mothers did not receive antenatal care (AOR = 4.4; 95% CI = 1.2 to 16.3; p = 0.023), or did not know any vaccine preventable disease (AOR = 13.3; 95% CI = 4.6 to 38.4; p < 0.001) were more likely to be ZD than their counterparts. In addition, perceptions of children's parents influenced child immunization. (4) Conclusions: Factors associated with being a ZD child suggest inequalities in vaccination that need to be addressed through appropriate interventions. Maternal and child health services need to be strengthened while also targeting children's fathers. This will make it possible to considerably reduce the proportion of ZD and undervaccinated children and effectively fight against VPDs.