Single arm, prospective open-label study of a care model consisting of two components: Component I aims to achieve high coverage of interventions to prevent maternal-to-child transmission of hepatitis B virus: antenatal tenofovir, and timely newborn administration of hepatitis B birth dose vaccine and hepatitis B immune globulin; Component II aims to achieve high coverage of screening, vaccination, and anti-viral therapy for HBV among household members of women with chronic HBV infection.

An estimated 248 million people worldwide are chronically infected with hepatitis B virus (HBV); and 75% of them live in Asia. Mother-to-child transmission (MTCT) accounts for the majority of chronic hepatitis B infections in Southeast Asia. Elimination of MTCT of HBV is theoretically possible with a comprehensive suite of interventions that includes birth dose vaccination, hepatitis B immune globulin, and antenatal antiviral therapy (e.g., tenofovir). However, the ideal gestational age to initiate antenatal tenofovir remains undefined; and evidence is lacking for implementation strategies capable of providing cost-effective, equitable access to a comprehensive suite of interventions to prevent MTCT of HBV in low-resource settings.

Component I: Prevention of Vertical Transmission Pregnant women living in the study area will be identified and screened for hepatitis B by a network of antenatal care (ANC) providers and existing community outreach workers; HBsAg positive patients will be invited to participate in the study. Consenting participants will provide serum samples to assess eligibility for anti-viral therapy: creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), platelet count, HCV, HIV. Pregnant women eligible for antiviral therapy according to WHO criteria, or who have viral load (VL) >200,000 IU/mL, will be treated with tenofovir starting at 20 weeks gestation through 4 weeks postpartum. Hospital-based delivery will be encouraged. All newborns, including those delivered at home, will receive the HBV birth dose vaccine within 24 hours of delivery, and newborns of women on tenofovir treatment will also receive Hepatitis B Immunoglobulin within 24 hours after delivery. Children will be linked to routine immunization services in Myanmar to complete their HBV vaccination series (HBV is co-formulated in a pentavalent vaccine). Maternal VL will be measured at delivery; infants will be tested for hepatitis B infection at 24-28 weeks postpartum.

Component II -- Household Screening and Treatment The household members of HBsAg positive pregnant women who consent to participate in the study will be screened for HBV-related immune status and chronic HBV infection. Non-immune individuals (HBsAb/Ag negative) will be vaccinated; HBsAg positive household members will be assessed for treatment eligibility and initiated on anti-viral therapy according to World Helath Organization guidelines. Eligible household members will also be screened every six months for hepatocellular carcinoma (HCC) by liver ulatrasound and alpha-fetoprotein levels

Qualitative Study:

In-depth interviews with approximately 30 HBsAg-positive women, 30 HBVsAg-negative women, and 20 household members of study participants will be conducted to assess barriers and facilitators related to HBV testing and treatment. Approximately 15 key-informant interviews with healthcare providers and community leaders will also be conducted. Sample size will depend on data saturation and will be adjusted based on results of data analysis during the study.

Inclusion Criteria:

• Pregnant women >= 18 years of age
• Gestational age =<34 weeks
• Test positive for HBsAg
• Live in study site area in South Dagon and Dagon Seikkan Townships, Yangon Region
• Give informed consent to participate in the study
• Newborns and household members of pregnant women enrolled in the study according to previous inclusion criteria

Exclusion Criteria:

• Alanine aminotransferase (ALT) levels >300 IU/L

For qualitative study:

Inclusion criteria

• Key informants (e.g., healthcare providers and community leaders in the study area) OR
• HBsAg+ women and their household members in the study area
• HBsAg- women and their household members in the stud area
• Give informed consent to participate in the study
• History of renal dysfunction
• CrCL < 50mL/min
• ALT>5 times the upper limit of normal (ULN)
• Evidence of decompensated cirrhosis (e.g., jaundice, ascites, history of upper gastrointestinal bleeding/esophageal varices, and hepatic encephalopathy)
• Any concomitant condition or treatment that, in view of the clinical site investigator, would contraindicate participation or satisfactory follow-up in the study HIV positive status unless 1) they are currently on additional ART therapy, or 2) their viral load is demonstrated to be <50 copies. Women who are newly diagnosed with HIV and referred to start a TDF-based regimen may be considered eligible once they have started the TDF-based regimen.
• Concurrent participation in any other clinical trial without written agreement of the study team
• Does not intend to deliver within catchment area, and/or intends to migrate before newborn follow-up is complete

The investigators are currently developing an individual participant data (IPD) sharing plan.