Most new hepatitis B virus (HBV) infections are acquired perinatally. In this study, pregnant women with HBsAg and HBeAg will receive tenofovir disoproxil fumarate during the last trimester of pregnancy and for two months following delivery. Their infants will receive hepatitis B (HB) immunization, starting with a first dose soon after birth. We hypothesize that the risk of mother-to-child transmission of HBV will be lower than 2%. The results of the study will help define policy to manage HBV infected pregnant women to prevent perinatal transmission.

This is a prospective multi-center, multi-country (Thailand and Lao PDR), open-label, single arm clinical trial in HBsAg and HBeAg positive pregnant women (from 28 weeks until one year postpartum) and their infants (until 18 months of age). Pregnant women with HBsAg and HBeAg will receive tenofovir disoproxil fumarate 300 mg once daily from 28 weeks of pregnancy until two months postpartum. Their infants will receive hepatitis B (HB) immunization, starting with the first dose soon after birth.

The study aims to show that substituting maternal antiviral treatment for infant HBIg can be favorably considered in settings where HBIg plus vaccine has been used as well as in settings where only vaccine is used. A significant improvement over the standard HBIg + vaccine strategy would be that adding an antiviral strategy results in less than 2% transmission. A total of 499 women and their infants will be enrolled in public hospitals in Thailand and Lao PDR.

The study will be monitored by a Data and Safety Monitoring Board (DSMB) at least annually.

Inclusion Criteria:

• Pregnancy
• Age ≥18 years
• Negative HIV antibody test during current pregnancy
• Positive HBsAg test during current pregnancy
• Positive HBeAg using a rapid test during current pregnancy
• Absence of clinical symptoms of liver disease
• Gestational age of 28 weeks (+/- 7 days) based on the obstetrician judgment guided by the review of the date of last menstruation period.
• Willing and able to provide written informed consent
• Agreeing to bring her infants(s) at the planned study visits at one of the study site until the last visit (18 months after birth) and to inform the site investigators if plans to move to another place and not be able to return to the clinic
• Understand the need for adequate infant immunization for her infant(s) and accept that blood draws will be performed to determine the infant HBV infection status

Exclusion Criteria:

• Receipt of anti-HBV antivirals at any time during the last 9 months
• Known liver cirrhosis or evidence of hepatocellular carcinoma
• Creatinine clearance <50 ml/min, calculated using the Cockcroft-Gault formula
• Confirmed dipstick proteinuria >1+ (>30 mg/dL) or normoglycemic glycosuria
• Evidence of pre-existing fetal anomalies incompatible with life
• Any concomitant condition or treatment that, in the view of the clinical site investigator, would contraindicate participation or compromise adherence to treatment and satisfactory follow up in the study.

Pregnant women

We are willing to share our data to answer important research questions requiring large datasets, after completion of the original research plan and substudies. Data-sharing agreements will include: an approval of the research plan by appropriate ethics committees, a commitment to using data for research purposes only and to securing the data or/and the samples using appropriate methods. Data used for publications will be released in a timely manner. De-identified study data will be accessible through the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Data and Specimen Hub or DASH (dash.nichd.nih.gov/).

However, as of May 25, 2025, the DASH website will be unable to support new submissions for the next several months. The PI will submit the data when new submissions are open.

At the same time as related publications

See Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Data and Specimen Hub or DASH