Vertical Transmission in Mothers Taking TAF With Exceptionally High Viral Load.

Published studies on tenofovir alafenamide (TAF) therapy for preventing vertical transmission of hepatitis B virus (HBV) have primarily enrolled mothers with viremic levels of approximately 7 log IU/mL. This study aimed to evaluate the efficacy and safety of TAF therapy in preventing mother-to-child transmission (MTCT) in mothers with exceptionally high viral loads, defined as HBV DNA levels > 2,000,000 IU/mL. Hepatitis B e antigen (HBeAg)-positive mothers with HBV DNA levels > 2,000,000 IU/mL were prospectively enrolled from four hospitals and initiated on TAF therapy between gestational weeks 26 and 28, continuing until delivery.