The COMBAT HBV Feasibility Trial

The overall study design is a randomized, double-blind, placebo-controlled trial among two groups of mother-infant dyads: women who receive TDF vs placebo in late pregnancy and the postpartum period (beginning at 28-32 weeks' gestation and continuing through 4 weeks' postpartum). While official World Health Organization (WHO) recommendations are to continue TDF at least through delivery, a range from delivery through 12 weeks' postpartum is possible; the investigators will continue therapy through 4 weeks' postpartum in this study. This feasibility trial will evaluate the acceptability, safety and preliminary effectiveness of a TDF-for-all approach to prevent MTCT of HBV in low-resource settings. HBsAg-positive pregnant women will be enrolled at 28-32 weeks' gestation, and will present for regular medication checks, with a study closeout visit at 24 weeks' postpartum. Study activities at monthly medication checks will include medication refills, assessment of adherence (via pill counts and verbal surveys), and evaluation for side effects. All infants will receive a birth-dose of HBV vaccine within 24 hours of life. MTCT of HBV will be defined as the proportion of infants with positive HBsAg testing at 6 months. This pilot study will provide preliminary data for sample size calculations, including safety and effectiveness data, to prepare for larger RCTs to determine the effectiveness of a tenofovir-for-all approach, as well as the added benefit of tenofovir over birth-dose vaccination.