A proposed trial of a hepatitis B vaccine on newborn babies in Guinea-Bissau has been cancelled following accusations that the trial was "unethical" and "neocolonial". The trial was funded by the US, under Health Secretary Robert F Kennedy Jr, who has a long record of expressing scepticism about vaccines. Police have seized a batch of vaccines from the research centre at the heart of the controversy.
The proposed trial drew international criticism because it planned to withhold a vaccine recommended by the World Health Organization (WHO) from half of the participating newborns. Some public health experts argued that the proposed trial raised broader questions about whether vulnerable populations in African countries were being asked to take risks that researchers would not accept in wealthier countries. The BBC has asked the US department of health and human services for comment.
The study was planned at the Bandim Health Project, a research centre that has operated in Guinea-Bissau since 1978. It 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 said the trial aimed to investigate whether the hepatitis B vaccine given at birth has broader health effects beyond preventing infection.
Previous studies in The Gambia and Guinea-Bissau have 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 have a unique opportunity to study its effects before such vaccines are introduced in 2028. But 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) $1.6m (£1.2m) in December 2025. Walter Kazadi Mulombo, the WHO representative in Guinea-Bissau, told the BBC they became concerned after receiving questions about the study and finding no publicly available protocol. He said the main ethical concern was that the trial would withhold an intervention already proven to protect newborns against hepatitis B.
"The vaccine has been used for more than 30 years in more than 115 countries," he said. "A study that will withhold that intervention from other newborns is unethical." He 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 the population of Guinea-Bissau are infected with hepatitis B, a viral infection that affects the liver.
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