Women were a mean of 28 weeks pregnant at baseline, with a mean viral load of 8.0 log10 IU/mL. Most women (about 90% of each group) had an HBV DNA of more than 200,000 IU/mL – a level associated with an increased risk of perinatal HBV infection despite vaccination.
There were 322 deliveries, resulting in 319 singletons, two pairs of twins, and one stillbirth. Postpartum infant treatment was quick, with a median of 1.3 hours from birth to administration of immune globulin and a median of 1.2 hours to administration of the first dose of the vaccine.
At 6 months, there were no HBV infections in the tenofovir-exposed group and 3 (2%) in the placebo group – a nonsignificant difference (P = .12).
Tenofovir was safe for both mother and fetus, with no significant adverse events in either group. The incidence of elevated maternal alanine aminotransferase level (more than 300 IU/L) was 6% in the tenofovir group and 3% in the placebo group, also a nonsignificant finding.