Controversial US-Funded Hepatitis B Vaccine Trial in Guinea-Bissau: Conflicting Reports and Ethical Outcry

A US-funded medical research trial, proposing to study the hepatitis B vaccine in newborns in Guinea-Bissau, has faced conflicting reports regarding its status and drawn significant criticism over its ethical design. While health authorities in Guinea-Bissau and the Africa Centres for Disease Control and Prevention (Africa CDC) announced the study's suspension, the U.S. Department of Health and Human Services (HHS) maintained that the trial is proceeding as planned.

Study Overview: Aims and Design

The proposed randomized controlled trial, funded by a $1.6 million grant from the U.S. Department of Health and Human Services (HHS) and the U.S. Centers for Disease Control and Prevention (CDC), aimed to observe 14,000 to 14,500 newborns in Guinea-Bissau. The study was led by Danish researchers Peter Aaby and Christine Stabell Benn and was initially slated to begin in early 2026.

Its stated objectives included investigating potential long-term neurological issues related to the hepatitis B vaccine. It also sought to assess broader health effects beyond hepatitis B protection, such as severe illnesses, eczema, or neurological differences before age five.

Research Design

The research design involved dividing newborns into two groups:

• One group (approximately 7,000 to 7,250 infants) would receive the hepatitis B vaccine at birth, aligning with World Health Organization (WHO) recommendations.
• The other group (approximately 7,000 to 7,250 infants) would receive the vaccine at six weeks of age, consistent with Guinea-Bissau's current vaccination practice, or later at 6, 10, and 14 weeks as part of routine immunizations.

The study was planned for a five-year duration and was structured as single-blinded, meaning investigators would be aware of group assignments, but parents would not.

Context in Guinea-Bissau: High Prevalence and Current Practices

Guinea-Bissau is a West African nation with a high prevalence of hepatitis B, affecting an estimated 18% of its adult population and 11% of children under one year of age. Infants who contract hepatitis B early in life face a 90% chance of developing chronic hepatitis B, with approximately a quarter potentially dying from severe complications like cirrhosis or liver cancer later in life.

The WHO recommends a birth dose of the hepatitis B vaccine for all children globally to prevent mother-to-child transmission. While the United States adopted this birth dose in 1991, Guinea-Bissau typically administers the initial dose at six weeks of age due to access issues. The country has plans to launch a universal birth dose program for infants by 2027 or 2028.

Ethical and Scientific Concerns Mount

The study's design drew extensive criticism from global public health experts and medical ethicists.

Critics argued that withholding the hepatitis B birth dose from half of the participants would knowingly deprive children of a proven, life-saving vaccine in a region with high disease prevalence.

Concerns were raised that this approach could lead to an increased incidence of hepatitis B infection in the delayed vaccination group. Some experts, including infectious diseases physician Paul Offit, compared the trial's design to the historical Tuskegee Study of Untreated Syphilis, where participants were denied life-saving treatment. Dr. Boghuma Titanji of Emory University characterized the study design as potentially exploitative of vaccine scarcity and governmental capacity in Africa.

Specific Design Flaws Highlighted

Additionally, questions were raised about:

• Study Focus: Critics noted the study was not designed to assess the efficacy of early versus delayed vaccination, as the benefit of early vaccination is widely established.
• Timeline: The five-year study duration was questioned, as chronic liver disease from perinatal hepatitis B infection typically manifests over several decades.
• Blinding: The single-blinded design raised concerns about potential investigator bias in assessing outcomes.
• Consent Process: Calls were made for clarity on whether the consent process for parents would adequately outline the risks associated with delayed vaccination.

Researchers' Defense

The researchers, Peter Aaby and Christine Stabell Benn, defended the study, stating it would provide the vaccine to some newborns who might not otherwise receive it. They also posited that the findings would enhance global scientific understanding of vaccination's impact on child health, arguing that certain vaccines might interfere with "non-specific effects" of other vaccines. They maintained that no newborn would receive fewer vaccines because of the study.

Funding and Approval Process Under Scrutiny

The $1.6 million grant from the U.S. government faced scrutiny over its approval process. The grant was awarded through a non-competitive process, with the selection of investigators occurring outside the standard bidding procedure. Emails indicated that Lyn Redwood and Stuart Burns, appointees under Health and Human Services Secretary Robert F. Kennedy Jr., assisted in advancing the non-bid grant. Stuart Burns, a senior adviser to the CDC director, reportedly conveyed that the study was a "funding priority for CDC/HHS." The grant was publicly posted in the Federal Register on December 18, two days after CDC announcements regarding hepatitis B vaccination recommendations.

Ethical Review Irregularities

Concerns were also raised about the ethical review in Guinea-Bissau. Quinhin Nantote, Guinea-Bissau's Minister of Public Health, stated that a local ethics committee (CNEPS) that initially approved the study lacked the necessary technical resources and did not coordinate with other national medical authorities.

An individual identifying as the CNEPS interim director confirmed initial approval but noted that the study proposal did not explicitly mention that some infants would go unvaccinated, which later became an ethical concern.

Reports also indicated that the Danish researchers did not seek approval from ethics boards in Denmark or the U.S., which the Helsinki Declaration generally requires for both sponsoring and host countries.

Conflicting Status Reports Spark Inter-Agency Dispute

On January 5, the proposed start date for the trial, contradictory reports emerged regarding its status:

Africa CDC and Guinea-Bissau Announce Suspension

Yap Boum, a senior official at the Africa CDC, announced the cancellation of the study, citing critical questions regarding its ethical design. Guinea-Bissau's Minister of Public Health, Quinhin Nantote, subsequently announced the study's suspension pending a review, attributing the situation to "misinformation, weak social communication means and a lack of international communication." Africa CDC Director-General Jean Kaseya affirmed support for Guinea-Bissau's sovereign decision and announced that Africa CDC experts would assist Guinea-Bissau in reviewing the study.

U.S. HHS Insists Trial Will Proceed

Andrew Nixon, a spokesperson for the U.S. Department of Health and Human Services (HHS), stated that the trial "will proceed as planned," asserting that the study had not been suspended and its protocol was being finalized.

Public Dispute and Sovereignty Claims

This led to a public dispute between HHS and Africa CDC.

Mr. Nixon questioned Africa CDC's credibility, describing its actions as a "public-relations campaign" and calling the organization "a powerless, fake organization."

In response, Africa CDC Director-General Jean Kaseya affirmed the organization's mandate from 55 African heads of state and government, stating that "no government has the right to impose experiments on the people of Guinea-Bissau," and emphasizing the country's sovereignty in health matters. Kaseya later reported that senior HHS officials stated they were unaware of Nixon's statement.

Africa CDC guidelines require any vaccine trial to have written authorization from the country's National Medicines Regulatory Authority, approval from the National Ethics Committee, a local institutional review board, and explicit approval from the Ministry of Health.

Researchers' History and Policy Intersections

Background of Danish Researchers

The Danish researchers, Peter Aaby and Christine Stabell Benn, are known for their hypothesis on non-specific vaccine effects, suggesting that while live-virus vaccines may reduce mortality, inactivated virus vaccines could increase it. Their research methods and findings have been subject to criticism, including a 2025 analysis by Danish statisticians documenting "questionable research practices."

They previously co-authored a 2018 study in Guinea-Bissau suggesting a link between the DTP vaccine and premature deaths in young girls, a finding they later revised in a subsequent publication. Concerns have also been raised about Dr. Aaby reportedly withholding results from a randomized clinical trial on the DTP vaccine for nearly 14 years.

Influence of U.S. Policy and Robert F. Kennedy Jr.

The study's emergence also occurred in the context of Robert F. Kennedy Jr.'s broader policy agenda regarding vaccinations. Kennedy, whose appointees advanced the grant, announced a policy shift in December 2025 to no longer universally recommend hepatitis B vaccinations, including the birth dose, in the U.S. He has publicly praised Aaby and Stabell Benn's research, citing it in support of his policy positions, including a decision to halt U.S. funding for Gavi, a global vaccine alliance.