Immunogenicity of a Birth Dose of Hepatitis B Vaccine in Kinshasa, Democratic Republic of Congo: A Randomised, Controlled Trial.

The WHO recommends hepatitis B birth-dose vaccination (HepB-BD), but it is not routinely given in most sub-Saharan African countries. We aimed to assess the immunogenicity of HepB-BD in addition to the existing hepatitis B vaccine (HepB3) schedule in Kinshasa, Democratic Republic of Congo among HBV-unexposed and HBV-exposed infants. Using an open-label, randomised, controlled design, HBV-unexposed infants were randomised (1:1) to receive the standard HepB3 vaccine series (group U3), or to receive HepB-BD in addition to HepB3 (group U4). A supplemental cohort of HBV-exposed infants (group E4) received HepB-BD and HepB3. We compared the proportion of infants with protective antibodies against HBV (HBV surface antibody ≥ 10 mIU/mL) between groups U3 and U4 and groups U4 and E4 at 12 months of age. Between August 20 and October 9, 2019, we enrolled 281 mother/infant dyads; 88 (31.3%) returned at 12 months. Most infants had protective antibodies against HBV at 12 months: 92.9% (75.7%-98.2%) in group U3, 85.7% (67.5%-94.5%) in group U4 and 96.9% (95% CI: 81.2%-99.6%) in group E4. Trends held in estimates adjusted for loss-to-follow-up (LTFU) and baseline imbalance across groups. In this first randomised trial assessing the addition of HepB-BD to the hepatitis B vaccine schedule in SSA, we found that HBV-unexposed infants who received the 3-dose and 4-dose vaccine series had similar immunogenicity against HBV at 12 months. A high proportion of infants, and notably HBV-exposed infants, had protective antibodies. Though extrapolation of findings may be limited by LTFU, this study adds real-world evidence regarding HepB-BD implementation in sub-Saharan Africa. Trial Registration: ClinicalTrials.gov identifier: NCT03897946.