Controversial Vaccine Trial Approved in Guinea-Bissau

Published: 10 October 2026. The English Chronicle Desk. The English Chronicle Online.

A controversial medical research project that plans to withhold the recommended birth dose of the hepatitis B vaccine from thousands of newborns in Guinea-Bissau has received approval from an ethics committee at the University of Southern Denmark, intensifying an international debate over research ethics, childhood vaccination and the protection of vulnerable communities. The trial, led by Danish researchers and expected to involve approximately 14,000 infants, has attracted criticism from medical experts who argue that deliberately delaying a proven preventive treatment could expose babies to avoidable health risks.

The study has also become politically significant because Robert F Kennedy Jr, the US secretary of health and human services and a prominent critic of established vaccination policies, has publicly praised the researchers behind the project. The controversy has raised questions about the influence of changing US vaccine policy on international research and whether standards applied to medical studies are sufficiently protective when trials take place in lower-income countries.

Under the proposed research design, half of the participating newborns would receive the hepatitis B vaccine at birth, while the remaining infants would not receive it during their first six weeks of life. Researchers intend to compare health outcomes between the groups, including mortality, skin conditions and neurodevelopmental outcomes. The study has been presented as an attempt to investigate the broader effects of vaccination, but critics say the design raises fundamental questions because the vaccine is already known to protect against a potentially serious infectious disease.

The project received approval from the Danish university’s ethics committee this week, while authorities in Guinea-Bissau have also authorised it to proceed. The decision is particularly contentious because the country’s health minister, Quinhin Nantote, had initially announced that the research was suspended following international criticism earlier in 2026. The latest approval indicates that the proposal has moved forward after changes to its protocol, although questions remain about how the revised safeguards will operate in practice.

Opposition has emerged not only from outside the committee but also from within it. Stig Børsen Hansen, a founding member who was among the reviewers presenting the study, resigned on Friday in protest. He argued that randomly assigning newborns to a group that would not receive the vaccine at birth effectively placed them in a lottery involving a preventable health risk. Three other committee members have also resigned in opposition to the decision.

Hansen’s objection centres on the ethical implications of exposing infants to a disease for which an established preventive intervention exists. Babies cannot consent to participation in research, and their parents must rely on researchers and ethics committees to ensure that any risks are justified by the potential benefits. Critics argue that the study places this responsibility under particular strain because the children in the delayed-vaccination group could encounter the virus before receiving protection.

Hepatitis B is a viral infection that can cause serious liver disease. Infection during infancy carries a particularly high risk of developing into chronic infection, which can eventually lead to cirrhosis or liver cancer. The virus can be transmitted from an infected mother to her child during birth, but exposure can also occur through contact with infected blood and other bodily fluids. In some circumstances, contaminated personal items and surfaces can contribute to transmission when they carry infected material.

Medical experts have stressed that infection is not limited to the immediate period surrounding delivery. According to research cited in the debate, a substantial proportion of children who acquire hepatitis B may become infected after birth through exposure within their communities. Paul Offit, an infectious disease specialist at Children’s Hospital of Philadelphia, has warned that the virus can survive on surfaces for up to seven days and may spread through shared items such as toothbrushes, washcloths and nail clippers when contaminated.

The revised trial protocol reportedly introduces additional precautions. Researchers will test mothers for hepatitis B before delivery, and babies whose mothers test positive will receive the vaccine and will not be enrolled in the study. Only infants whose mothers test negative may be eligible for participation. The updated protocol has not been made publicly available, however, leaving independent observers unable to assess all its provisions.

Critics say maternal screening does not eliminate the risk. A hepatitis B test can produce a false-negative result, meaning an infected mother may be incorrectly classified as uninfected. If that occurs, her newborn could be included in the group that does not receive the vaccine at birth despite being at risk of infection. Researchers and ethics reviewers will therefore face questions about whether the proposed screening procedures can provide adequate protection for every infant involved.

The controversy is further complicated by the difference between vaccination policies in Guinea-Bissau and Denmark. Guinea-Bissau has among the world’s highest hepatitis B prevalence rates, with approximately 18% of adults reported to carry the virus. The country had planned to introduce universal hepatitis B vaccination for newborns in 2027, but the campaign has been postponed until 2028. Critics argue that the delay should not become an opportunity to withhold a preventive intervention from infants who might otherwise be protected.

In Denmark, newborns are not routinely given the hepatitis B vaccine when their mothers test negative for the virus, although pregnant women are screened. Henrik Støvring, a professor of statistics and pharmacometrics at Aarhus University, has questioned why researchers could not conduct the trial in Denmark if they believe the scientific question warrants investigation. The contrast has become central to concerns that the study places the greatest burden of uncertainty on children in a country where infection is considerably more common.

The research is associated with the Bandim Health Project, a long-running programme operated by Danish researchers Peter Aaby and Christine Stabell Benn in Guinea-Bissau. The project has maintained a substantial presence in the country’s health system for decades. Its close connections with local public health institutions have prompted additional scrutiny over the independence of decision-making and the relationships between researchers, officials and the national healthcare system.

Funding has also attracted attention. The US Centers for Disease Control and Prevention has reportedly allocated $1.6 million for the project in its budget for the year, with additional private support expected from the Pershing Square Foundation, co-founded by billionaire investor Bill Ackman, and the Bluebell Foundation. The CDC, the researchers, the foundations and the country’s health minister had not responded to questions about the trial at the time of the original report.

Kennedy’s support has added another layer to the dispute. At an anti-vaccine conference last month, he praised the Danish researchers and described them as leading figures in vaccine research. He also cited earlier research to argue that vaccination could be associated with serious harm. Critics have challenged the interpretation of those findings, pointing out that a subsequent follow-up study by the same researchers reportedly found no effects.

The proposed Guinea-Bissau study will examine mortality alongside several other health outcomes. Supporters may argue that further research could help clarify whether vaccines have effects beyond their intended protection against particular infections. Opponents counter that investigating speculative wider effects cannot justify exposing newborns to a known infectious risk when the benefits of hepatitis B vaccination are well established.

International research ethics standards, including the principles reflected in the Declaration of Helsinki, require medical research involving human participants to undergo appropriate independent ethical review. Questions have arisen over the Danish committee’s role because it had not previously reviewed medical studies of this kind and changed its rules to consider the proposal. Denmark’s national ethics system generally oversees medical research within its jurisdiction, while the Guinea-Bissau trial is to take place abroad. This has fuelled debate over which institutions should bear responsibility for evaluating the study and ensuring that its participants are adequately protected.

The Africa Centres for Disease Control and Prevention has opposed the trial, according to the report, and has indicated that discussions between US and Guinea-Bissau authorities are continuing. The disagreement highlights a wider challenge in international medical research: ensuring that decisions about studies involving vulnerable populations are made transparently, with meaningful local oversight and safeguards consistent with accepted medical standards.

The central question is whether the potential scientific value of the trial can justify delaying vaccination for some newborns in a country where hepatitis B is widespread. For the researchers, the study is intended to examine health outcomes that they believe require further investigation. For critics, its design risks placing children in harm’s way to answer questions that could be investigated through less ethically contentious approaches.

As preparations move forward, the revised protocol, the quality of maternal screening, the consent process and the independence of the ethical review are likely to remain under intense scrutiny. The controversy also underscores the need for transparent communication with families and local communities, particularly when research decisions may affect children who cannot make choices for themselves.

The outcome could have implications beyond Guinea-Bissau, influencing debates about vaccine policy, the conduct of international clinical trials and the responsibilities of governments and research institutions that fund or approve studies abroad. Until further details are made public and the outstanding ethical concerns are addressed, the trial is likely to remain a focal point in the wider debate over how scientific inquiry can advance without compromising the safety and rights of its most vulnerable participants.