Effectiveness of timely hepatitis B birth dose vaccination to prevent mother-to-child transmission in Ethiopia.

BACKGROUND: Mother-to-child transmission (MTCT) is an important route of new hepatitis B virus (HBV) infections. In Africa, limited and conflicting data on the effectiveness of hepatitis B birth dose vaccination (HepB-BD) have contributed to fragmented adoption and sub-optimal implementation. We aimed to assess the effectiveness of timely HepB-BD in preventing HBV MTCT in Ethiopia. METHODS: We conducted a multi-centre cross-sectional observational study in Ethiopia from May 2022 to June 2024. We identified mothers who had tested positive for hepatitis B surface antigen (HBsAg) during pregnancy and assessed mother-infant pairs at 6-12 months post-partum for HBV MTCT. We stratified effectiveness of HepB-BD by maternal risk profile (HBV DNA level, hepatitis B e-antigen (HBeAg) status). RESULTS: The analysis included 387 children born to HBV-positive, HIV-negative mothers who had completed routine HBV vaccination (HepB3). The median age of infant testing was 10 months (IQR 7.0-11). Overall MTCT risk was 5.2% (95% CI 3.4,7.8). MTCT was significantly lower among infants receiving HepB-BD alone (0/39, 0% [95% CI 0-9.0]) compared to those without immunoprophylaxis at birth (20/131, 15.3% [95% CI 10.1-22.4]) (p = 0.009). No transmission occurred with HepB-BD plus HBIg (0/217, 0% [95% CI 0-1.7]). Maternal viral load >200,000 IU/ml (AOR 16.6, 95% CI 4.82,57.19) and HBeAg positivity (AOR 4.21, 95% CI 1.08,16.44) were associated with increased MTCT risk amongst infants without immunoprophylaxis at birth. CONCLUSIONS: In Ethiopia, the current vaccination series starting at 6 weeks is insufficient to prevent HBV MTCT. Timely HepB-BD is highly effective in reducing HBV MTCT and should be prioritised for scale-up in Africa.