Guinea-Bissau is suspending a hepatitis B vaccine study involving newborns while it awaits an ethical review, Health Minister Quinhi Nantot said Thursday.

Nantot said a six-person ethics committee did not meet to review the study during an initial confirmation process. He made the remarks during a news conference held by the Africa Centers for Disease Control and Prevention, according to the Associated Press.

The study is designed as a randomized controlled trial. Under the plan described by AP, some infants would be given the hepatitis B vaccine at birth, while others would not, and researchers would track children for death, illness and long-term developmental outcomes.

Some experts have suggested the research plan is unethical, AP reported, saying it would withhold vaccines that they say work from newborns at significant risk of infection.

Africa CDC Director-General Jean Kaseya said he fully supports the ethical review. He also said in remarks during the conference that Africa CDC is “led by the interests of our people in Africa,” and not by “the small interests of individual people.”

U.S. health officials said Wednesday that the study is still set to proceed, AP reported. Andrew Nixon, a spokesman for the U.S. Department of Health and Human Services, said in a statement that “The study is proceeding as planned, and we continue to work with our partners to finalize the study’s protocols.”

The AP reported that the Trump administration awarded a $1.6 million, no-bid contract to a Danish university to study hepatitis B vaccinations in newborns in Guinea-Bissau. The report said the contract was awarded to scientists who have been cited by anti-vaccine activists and whose work has been questioned by leading public health experts.

AP said research and widespread medical consensus hold that the hepatitis B vaccine protects newborns, and that withholding it from some babies has raised ethical alarms. The AP also reported that the U.S. Centers for Disease Control and Prevention awarded a grant to a research team at the University of Southern Denmark.

In addition, the AP reported that the team was lauded by U.S. Health Secretary Robert F. Kennedy Jr., and that one of the team’s leaders is Christine Stabell Benn. AP described Benn as a consultant for a Kennedy-appointed committee that recently voted to stop recommending a dose of hepatitis B vaccine for all American newborns.

The AP said the study was set to begin early this year in Guinea-Bissau, an impoverished West African nation where hepatitis B infection is common. Researchers were funded for five years to study 14,000 newborns.

AP reported that most of the children would be followed for less than two years to look for side effects. The first 500 enrolled would be followed for five years to look for behavior and brain development problems, and AP said there was no placebo involved as initially designed.

Nixon did not release any other details about the current version of the study design, AP reported.