The COMBAT HBV Feasibility Trial (COMBAT-HBV)

February 18, 2026 updated by: University of North Carolina, Chapel Hill

Simplifying Hepatitis B Care in Pregnancy by Combining Birth-dose Vaccine and Tenofovir: The COMBAT HBV Feasibility Trial

This is a double-blind, randomized placebo-controlled trial (RCT) of a prophylaxis-for-all approach to prevention of mother-to-child transmission (PMTCT) of hepatitis B virus (HBV) in the Democratic Republic of Congo (DRC). HBV-infected pregnant women will be randomized to either receive tenofovir or placebo beginning at 28-32 weeks' gestation and continuing through 4 weeks' postpartum. Women will be followed every 4-6 weeks throughout the prenatal and postpartum period to evaluate for side effects related to the medication. Infants will receive a birth-dose of HBV vaccine, ideally within 24 hours. Participants will be followed longitudinally through 6 months' postpartum.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

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.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
317

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Pregnant women ≥18 years of age who present for routine prenatal care between 28-32 weeks' gestation and who test HBV-positive by point-of-care hepatitis B surface antigen test. Women must intend to seek maternity and postpartum care exclusively at one of the Kinshasa-based study maternity centers.
  • Infants born to enrolled women will be included in the study

Exclusion Criteria:

  • Individuals with abnormal creatinine by point-of-care testing
  • Any woman who plans to move outside of Kinshasa Province during the study period.
  • Any HIV-positive individual, determined by routine point-of-care screening at antenatal care visits

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Tenofovir disoproxil fumarate (TDF) arm
140 pregnant women in the experimental arm will receive tenofovir disoproxil fumarate (TDF) 300 milligrams (mg) daily, beginning at 28-32 weeks' gestation and continuing through 4 weeks' postpartum. Infants born to these women will be included in this arm and will receive a birth-dose of hepatitis B vaccine.
Biological: Hepatitis B monovalent vaccine
All infants born to women in the study will receive a birth-dose hepatitis B vaccine.
Other Names:
  • Engerix-B
  • Hepatitis B birth-dose vaccine
Drug: Tenofovir Disoproxil Fumarate 300 MG
Pregnant women in the experimental arm will receive TDF daily beginning in the 3rd trimester of pregnancy and continuing through 1 month postpartum.
Other Names:
  • Viread
Placebo Comparator: Placebo arm
140 pregnant women in the placebo arm will receive a placebo pill daily, beginning at 28-32 weeks' gestation and continuing through 4 weeks' postpartum. Infants born to these women will be included in this arm and will receive a birth-dose of hepatitis B vaccine.
Biological: Hepatitis B monovalent vaccine
All infants born to women in the study will receive a birth-dose hepatitis B vaccine.
Other Names:
  • Engerix-B
  • Hepatitis B birth-dose vaccine
Drug: Placebo
Pregnant women in the placebo arm will receive a placebo pill daily beginning in the 3rd trimester of pregnancy and continuing through 1 month postpartum.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Safety (Pregnant Women): Number of Pregnant Women With Adverse Effects Related to Study Medications
Time Frame: Up to study close-out visit, or up to 12 months
Safety of TDF prophylaxis in pregnant women, defined as a composite of adverse events (# mild adverse events [AEs], # moderate-to-severe AEs), presence of side effects and alanine aminotransferase elevations ≥ 5x upper limit of normal
Up to study close-out visit, or up to 12 months
Safety (Infants): Number of Infants with Adverse Effects Related to Study Medications
Time Frame: At delivery
Safety of maternal TDF for infants, defined as a composite of: Birth weight (grams), mid-upper arm circumference (centimeters), gestational age at delivery (weeks and days), delivery mode (vaginal vs C-section), APGAR scores (0-10), # of adverse events
At delivery
Feasibility (Recruitment): Number of Eligible Participants Who Were Enrolled in the Study
Time Frame: Up to study close-out visit, or up to 12 months
Recruitment is indicative of the number of pregnant women who are screened versus those actually enrolled in the study.
Up to study close-out visit, or up to 12 months
Feasibility (Refusal): Number of Eligible Participants Who Refused to Enroll in the Study
Time Frame: Up to study close-out visit, or up to 12 months
Refusal will be defined as the number of individuals who refuse enrollment upon initial recruitment.
Up to study close-out visit, or up to 12 months
Feasibility (Withdrawal): Number of Enrolled Participants Who Withdraw from the Study
Time Frame: Up to study close-out visit, or up to 12 months
Withdrawal is indicative of the number of enrolled participants who choose not to continue study activities after having been enrolled.
Up to study close-out visit, or up to 12 months
Feasibility (Retention): Number of Enrolled Participants Who Remain in the Study Through 6 Months Postpartum
Time Frame: Up to study close-out visit, or up to 12 months
Retention is defined as the number of participants who remain in the study through the 6-month postpartum visit.
Up to study close-out visit, or up to 12 months
Feasibility (Maintenance): Proportion of Study Visits Completed Per Participant
Time Frame: Up to study close-out visit (12 months)
Adherence to study visits and procedures, defined as proportion of the actual number of visits attended divided by the expected study visits (8) and multiplied by 100.
Up to study close-out visit (12 months)
Acceptability (Lab Testing): Number of Mothers With Lab Testing Acceptability Scores >80%
Time Frame: Upon study close-out visit, or up to 12 months
Number of mothers who report the process of undergoing lab draws as "acceptable" in the exit survey. Range 0-100%, with 0% being unacceptable and 100% being acceptable.
Upon study close-out visit, or up to 12 months
Acceptability (Medication): Number of Mothers With Medication Acceptability Scores >80%
Time Frame: Upon study close-out visit, or up to 12 months
Number of mothers who report the process of taking the study medication as "acceptable" in the exit survey. Range 0-100%, with 0% being unacceptable and 100% being acceptable.
Upon study close-out visit, or up to 12 months
Preliminary Effectiveness: Number of Infants With HBV Positivity by Rapid Diagnostic Testing at 6 Months of Life to Indicate Mother-to-Child Transmission of HBV
Time Frame: Measured at 6 months after birth
Mother-to-child transmission of HBV is defined as HBsAg positivity in the infant at 6 months of life.
Measured at 6 months after birth

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Sensitivity of the Hepatitis B Core-Related Antigen Test
Time Frame: Measured at Enrollment
Sensitivity will be defined as the number of true positive tests divided by the sum of the true positives and false negatives.
Measured at Enrollment
Specificity of the Hepatitis B Core-Related Antigen Test
Time Frame: Measured at Enrollment
Specificity will be defined as the number of true negative tests divided by the sum of the true negatives and the false positives.
Measured at Enrollment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of North Carolina, Chapel Hill

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Albert Einstein College of Medicine
Abbott
Doris Duke Charitable Foundation
Université Protestant au Congo

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Peyton Thompson, MD, MSCR, University of North Carolina, Chapel Hill

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 17, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 25, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 25, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 20, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 20, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 30, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 19, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 22-1492

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Datasets will not be made publicly available because they contain protected health information. However, the authors will share de-identified participant data, alongside the study protocol, statistical analysis plan, and analytic code, upon reasonable request and with approval by an independent review committee (ie, learned intermediary). An executed Data Use/Sharing agreement with the University of North Carolina at Chapel Hill (UNC-CH) is required before data will be shared

IPD Sharing Time Frame

Data will be available from 9 to 36 months after publication.

IPD Sharing Access Criteria

Interested individuals can request de-identified data with approval from an independent review committee, which will be shared upon execution of a Data Use/Sharing Agreement with UNC-CH.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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