Determinants of the uptake of childhood immunization in Kinshasa Province, the DRC: ordered logit regression analyses to assess timely infant vaccines administered at birth and six-weeks of age.

Abstract Background: Despite global efforts to reduce preventable childhood illness by distributing infant vaccines, immunization coverage in sub-Saharan African settings remains low. Further, timely administration of vaccines at birth – tuberculosis (Bacille Calmette-Guérin [BCG]) and polio (OPV0) – remains inconsistent. Countries such as Democratic Republic of the Congo (DRC) prepare to add yet another birth-dose vaccine in their immunization schedule, but research is necessary to understand the determinants of current birth-dose vaccines’ timely administration. This study aims to improve current and future birth-dose immunization coverage by understanding determinants of infants receiving vaccinations within the national timeframe. Methods: The study used two ordered regression models to assess barriers to timely BCG and first round of hepatitis B (HepB3) immunization across multiple time points using the Andersen Behavioral Model to conceptualize determinants at various levels. The assessment leveraged survey data collected during a continuous quality improvement study (NCT03048669) conducted in 105 maternity centers throughout Kinshasa Province, DRC. The final sample included 2,398 (BCG analysis) and 2,268 (HepB3 analysis) women-infant dyads living with HIV. Results: Between 2016 and 2020, 1,981 infants (82.6%) received the BCG vaccine, and 1,551 (68.4%) received the first dose of HepB3 vaccine. Of those who received the BCG vaccine, 26.3, 43.5%, and 12.8% received BCG within 24 hours, between one and seven days, and between one and 14 weeks, respectively. Of infants who received the HepB3 vaccine, 22.4% received it within six weeks, and 46% between six and 14 weeks of life. Many factors were positively associated with BCG uptake, including higher maternal education, household wealth, higher facility general readiness score, and religious-affiliated facility ownership. The factors influencing HepB3 uptake included older maternal age, higher education level, household wealth, transport by taxi to a facility, higher facility general and immunization readiness scores, and religious-affiliated facility ownership. Conclusion: This study demonstrated that the study participants’ uptake of vaccines was consistent with the country average, but not in a timely manner. Various factors were associated with timely uptake of BCG and HepB3 vaccines. These findings suggest that investment to strengthen the vaccine delivery system might improve timely vaccine uptake and equity in vaccine coverage.