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

ABSTRACT 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