A proposed trial of a hepatitis B vaccine on newborn babies in Guinea-Bissau has been canceled following accusations that the trial was "unethical" and "neocolonial." The trial, funded by the U.S. under Health Secretary Robert F. Kennedy Jr., drew international criticism because it planned to withhold a vaccine recommended by the World Health Organization (WHO) from half of the participating newborns.
Police have seized a batch of vaccines from the research center at the heart of the controversy, the Bandim Health Project, which has operated in Guinea-Bissau since 1978. The study was designed to involve 14,000 newborns, with half receiving a hepatitis B vaccine shortly after birth and the other half not being given the shot. Bandim stated the trial aimed to investigate whether the hepatitis B vaccine given at birth has broader health effects beyond preventing infection, citing previous studies in The Gambia and Guinea-Bissau that raised questions about a possible link to increased mortality. Researchers argued that because Guinea-Bissau does not currently offer routine hepatitis B vaccinations at birth, despite WHO recommendations, they had a unique opportunity to study its effects before such vaccines are introduced in 2028. However, critics questioned the ethics of withholding the vaccine from some babies, particularly in one of the world's poorest countries where the infection is widespread. The Trump administration funded the proposed study, with the CDC awarding the University of Southern Denmark (SDU) $1.6 million in December 2025.
The WHO representative in Guinea-Bissau, Walter Kazadi Mulombo, told the BBC that the organization became concerned after finding no publicly available protocol for the study. He stated the main ethical concern was that the trial would withhold an intervention already proven to protect newborns against hepatitis B, noting that the vaccine has been used for more than 30 years in over 115 countries. Mulombo warned that babies could be exposed to the virus during childbirth if their mothers were infected, as well as later in life. Nearly a fifth of Guinea-Bissau's population is infected with hepatitis B, a viral infection that affects the liver. The WHO is working with the government to accelerate the introduction of the birth-dose vaccine, which was initially expected in 2028 but is now being considered for early 2026.
Guinea-Bissau's government prohibited hepatitis B vaccine trials involving children in January and requested an evaluation from the Africa Centres for Disease Control and Prevention. Health Minister Quinhin Nantote expressed surprise and outrage at media reports claiming the trial might proceed, stating that even he had not been informed. The dispute intensified after SDU claimed a revised study protocol had received ethical approval from "the relevant authorities in Guinea-Bissau," which Nantote denied. Dr. Gavin Yamey, a professor at Duke University, criticized the proposal as "reeking of neocolonialism," questioning why the research was not being conducted in Denmark. SDU dean Jakob Grauslund maintained that the trial had never started, no babies were enrolled, and no vaccinations were administered as part of the research.
The SDU stated it had received a separate, positive assessment from its own research ethics committee. Grauslund added that the university had sought an additional independent assessment, though Danish law did not require one. He stressed that this did not replace the authorization required from Guinea-Bissau's authorities.
On October 19, Guinea-Bissau's Judicial Police searched the Bandim Health Project's facilities and seized a batch of hepatitis B vaccines. Police said the batch was intended for vaccinating children but did not disclose the number of doses or the grounds for the investigation, emphasizing that the seizure did not necessarily mean the vaccines were defective or unsafe. The police have not explicitly linked their investigation to the proposed trial.
The proposed trial was funded by the U.S. government during a period of significant changes to vaccine policy under President Donald Trump and Health Secretary Kennedy. Critics had questioned whether the research could support a policy shift away from routine hepatitis B vaccination at birth, although the study's stated aim was to investigate potential effects beyond preventing infection. Kennedy had previously praised the Danish researchers and cited earlier findings from their work in support of concerns about vaccine safety, though a subsequent study by some of the same researchers found no evidence of previously reported effects. The available information does not suggest the proposed trial was designed to justify a change in U.S. policy.