In a significant development, a contentious research project on hepatitis B vaccinations for newborns in Guinea-Bissau, funded by the United States, has been called off. This decision was announced by Yap Boum, a prominent figure at the Africa Centres for Disease Control and Prevention (CDC), during a media briefing on Thursday morning.

“The study has been cancelled,” Boum stated to the press, confirming the termination of the $1.6 million initiative. This study, which operated under the aegis of Robert F. Kennedy Jr., a known critic of vaccines, was met with fierce opposition. Critics voiced ethical concerns over the study’s design, which involved withholding vaccines that are crucial in preventing hepatitis B in a country where the disease is notably prevalent.

Boum emphasized the importance of conducting research that can inform policy in Africa but highlighted the necessity of adhering to ethical standards. “It’s of importance for Africa CDC to have evidence that can be translated into policy, but this has to be done within the norm. So we are glad that at this point the study is being cancelled,” he explained. The study’s design posed significant ethical challenges, prompting its cancellation.

Despite the study’s cancellation, officials in Guinea-Bissau indicated that the trial could still proceed. However, Africa CDC officials clarified that any future trial would need to undergo a redesign to meet ethical standards. Boum mentioned ongoing discussions between Guinea-Bissau and US officials on how to ethically conduct such a trial. Furthermore, Africa CDC has formed a team to ensure that Guinea-Bissau receives the necessary support to align any future study with ethical regulations.

Details of the study’s design have not been publicly disclosed by the researchers or health authorities. Nonetheless, a leaked version of the study was published by Inside Medicine on Thursday. Following this leak, an official from the US Department of Health and Human Services (HHS) informed the Guardian that the trial protocol is currently under revision, and the leaked version does not represent the finalized plan. As a result, the trial, as initially proposed, will not proceed.

The design of the study has not been made public by the researchers or by health officials, but a leaked version was published by Inside Medicine on Thursday. An HHS official told the Guardian after publication that the protocol is now being updated and the leaked version is not finalized. That would mean the trial would not proceed as it has been described so far.

The official did not offer a timeline for when the study would be finalized, but said the US was trying to move as quickly as possible before vaccines roll out to all Guinea-Bissau newborns in 2027. “This study is going to proceed as planned,” the official said.

Guinea-Bissau, which underwent a coup in November, appears to have replaced all top officials, including at the ministry of health. Previous officials did not respond to media inquiries, and the number and email address for the health ministry appear to be disconnected.

“The good guys won,” said Paul Offit, an infectious diseases physician at the Children’s Hospital of Philadelphia and a former member of the vaccines and related biological products advisory committee for the US Food and Drug Administration (FDA). The cancellation news was “extremely heartening”, he said, adding that except for the birth of his children, he had “never been happier”.

“This administration did not see people in Africa as valuable,” Offit said. “You can’t treat children like this, you can’t treat people like this. We were able to stand up for them. We were able to convince people about the fact that this was unethical.”

The news could represent a turning point for Guinea-Bissau and other countries where researchers are conducting work that critics say is unethical. It shows that “the institutions are getting stronger” by pushing back on unethical and exploitative studies in Africa, said Boghuma Titanji, an assistant professor of medicine at Emory University who is studying vaccine misinformation in Africa.

The halt was “a win for advocacy and upholding the ethics of research”, said Titanji, who called the trial as it seems to be designed a “damaging study”. “It can lead to damage that lasts for several decades after the study has been completed,” said Titanji.

The researchers argued that the trial would make the vaccine available to 7,000 newborns when they would “not otherwise receive it”. But that means the other 7,000 children in the trial would not have access to the vaccine “due to the flip of a coin”, which would “knowingly deprive 7,000 children of a vaccine that could save their lives”, Offit said. Instead, he said, “take the $1.6m and vaccinate as many children as you can at birth”.

About 18% of adults and about 11% of children under the age of one in Guinea-Bissau have hepatitis B. Children are much more likely to develop long-term effects, such as liver cirrhosis, which can lead to cancer and death if they catch the virus when they are very young.

Guinea-Bissau currently recommends the hepatitis B vaccine for all babies at six weeks of age because of issues accessing the vaccine, but that recommendation will change to all newborns at birth in 2027, when more doses are available.

Offit likened the trial to the Tuskegee experiment, in which US researchers knowingly withheld an effective antibiotic from African American men suffering from syphilis.

The Danish researchers conducting the trial have also been criticized for not publishing the results of a study on the diphtheria-tetanus-pertussis (DTP) vaccine, potentially because it contradicted their belief that the vaccine is dangerous, according to the Danish journalist Gunver Lystbæk Vestergård.

The protocols for the study have not been made public by the researchers or health officials, but a leaked version was published by Inside Medicine. Frederik Schaltz-Buchholzer, one of the Danish researchers, also shared some details on social media. Titanji didn’t find his argument compelling. “It actually just raises even more concerns in my mind,” she said.

The researchers argue that some types of vaccines may bring nonspecific effects – improving overall health, not just against the disease the vaccine is targeting. But, they say, adding other kinds of vaccines, such as that for hepatitis B, could interfere with these possible effects. Yet the evidence to support possible overall health effects is based upon the researchers’ prior research, which has been called into question.

Other Danish researchers analyzed these studies and found no statistically significant effects, according to their new preprint study, which has not been peer-reviewed or published yet. One of the researchers on that study, Anders Hviid, said on LinkedIn that these findings were especially important given recent decisions in the US to limit several vaccines for children.

The Danish researchers also argued that trials should be done in Africa in order to study their effects on African children.

Titanji agreed that there needed to be more randomized controlled trials done in Africa on Africans, but said that they should be led by African scientists and powered by questions from Africans. Projects like the Danish study “basically exploit the scarcity of a proven beneficial vaccine in a context where that vaccine is needed”, Titanji said. The study, as it is currently designed, would be “exploiting a window where the government is not able to provide that intervention to its citizens”, Titanji added. “You are not solving the problem. You’re actually being part of the problem.”

The trial was slated to begin on 5 January. When asked last week about whether the trial had begun, the lead researchers, Peter Aaby and Christine Stabell Benn, disputed the Guardian’s previous story that cited ethical concerns.

“That article was totally wrong,” Aaby said. “The report had virtually no evidence-based content about vaccines to transmit to the readers, only a lot of ethical condemnations from those who might potentially be questioned by the future results of the study.”

Aaby and other researchers on the project did not respond to further inquiries about the project’s cancellation.

Aaby and Stabell Benn, who are Danish researchers, have close ties with Trump administration health officials. Stabell Benn hosted a podcast with Tracy Beth Høeg, now an FDA official who has worked to find deaths after Covid vaccination and advocated for the US to slash vaccine recommendations to align with Denmark’s schedule.

On Joe Rogan’s podcast in 2023, Kennedy praised Aaby as a “very famous” researcher whose work showed the DTP vaccine was deadly, he said – research Kennedy also cited when he ended funding to Gavi, the Vaccine Alliance. But he didn’t mention that the year before, in 2022, the researchers found completely different results when they conducted the same trial.