8-week TAF course enough to prevent mother–child HBV transmission

An 8-week course is as good as a 12-week course of tenofovir alafenamide fumarate (TAF) therapy in terms of preventing the transmission of hepatitis B virus (HBV) infection from mothers to infants, as reported in a study.

At 7 months postpartum, the vertical transmission rates did not differ by the duration of prophylactic TAF treatment, according to the investigators led by Dr Qing-Lei Zeng from the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.

The vertical transmission rates in the 8- and 12-week groups were 7.6 percent versus 6.7 percent (p=0.788) in the intention-to-treat analysis, respectively, and both 0 percent in the per-protocol analysis. [AASLD 2023, abstract 5012-C]

“TAF was well tolerated, and no one discontinued therapy due to adverse events,” Zeng noted.

A mild elevation in alanine aminotransferase levels occurred in 15.1 percent of patients in the 8-week group and in 18.3 percent of those in the 12-week group (p=0.507).

Furthermore, there were no incidences of birth defects in either group. All infants exhibited normal physical and neurological growth at birth and at 7 months.

“Several latest international guidelines recommended 9 to 30 weeks of maternal antiviral prophylaxis to prevent mother-to-child transmission of HBV,” Zeng pointed out.

The present data showed that the “expected 8-week TAF treatment to prevent [vertical transmission] is generally safe and effective,” he added.

For their multicentre, open-label, noninferiority study, Zeng and colleagues recruited 239 pregnant women with HBV DNA of 5.3–9.0 logs IU/mL from six Chinese referral hospitals. These women were randomly assigned to receive TAF from the first day of 33 gestational weeks to delivery date (expected 8 weeks) or the first day of 33 gestational weeks to delivery date to postpartum month 1 (expected 12 weeks).

All mother–infant dyads were followed until 6 months postpartum, and every infant received standard immunoprophylaxis. A total of 119 and 120 pregnant women in the 8- and 12-week groups, respectively, were included in the intention-to-treat analysis, and 110 and 112, respectively, in the per-protocol analysis.

At delivery, 96.5 percent of women in the 8-week group and 97.4 percent of those in the 12-week group achieved HBV DNA <5.3 log10 IU/mL.

Zeng called for additional large-scale studies to validate the findings and establish the benefits of 8-week prophylactic treatment with TAF.

The exact mechanism and timing of perinatal HBV transmission are unclear. While most infections occur during childbirth, there is also evidence of transmission taking place before birth and through horizontal transmission after birth. HBV DNA and HBsAg have been detected in amniotic fluid, placental cells, and umbilical cord blood, suggesting the possibility of transplacental HBV transmission. [Obstet Gynecol Surv 2012;67:37-44; J Med Virol 2002;67:20-26; Am J Obstet Gynecol 2001;185:981-987; World J Gastroenterol 2004;10:437-438]