A controversial hepatitis B vaccine trial in newborns in Guinea-Bissau — funded by the US Centers for Disease Control and Prevention (CDC) and publicly championed by Health Secretary Robert F. Kennedy Jr. — will not go forward, the study’s lead researcher said Wednesday, ending a months-long fight that had drawn widespread condemnation from vaccine scientists and global health ethicists.
“It is now clear” that the study “will not move forward in Guinea-Bissau,” wrote Frederik Schaltz-Buchholzer, a Danish researcher affiliated with the Bandim Health Project, in a post on LinkedIn. He added that the research team “were not given the necessary governmental approval.”
The announcement reverses an earlier decision by authorities in the West African nation to allow the trial to proceed — a go-ahead that had itself been reported internationally and celebrated by supporters of the study — and closes, at least for now, one of the most contentious episodes in the recent history of American global health policy.
What the study proposed
The trial was designed to test whether the timing of the birth-dose hepatitis B vaccine alters the shot’s broader, “non-specific” effects on infant mortality and immune development — a hypothesis long associated with the Bandim Health Project, which has for decades studied how vaccines interact with overall health in Guinea-Bissau. Newborns would have been randomly assigned to receive the vaccine at birth or on a delayed schedule.
That design drew fierce criticism. Guinea-Bissau has significant hepatitis B prevalence, and the World Health Organization recommends a birth dose precisely to prevent mother-to-child transmission. Critics argued that randomizing some infants to a delayed dose would deny them a proven protective benefit, and that the study could not meet the ethical bar required for research on vulnerable newborns in a low-income country.
Supporters countered that all infants would eventually be vaccinated and that the question — whether timing affects mortality — is one of genuine scientific importance, particularly for countries where birth-dose coverage remains uneven.
A political lightning rod
The study’s profile rose sharply as it became entangled in American politics. Kennedy, a longtime vaccine skeptic who has questioned the safety of the hepatitis B birth dose, touted the trial publicly, turning it into a symbol of his stated ambition to re-examine the vaccine schedule. Reporting from Rolling Stone and others traced how the CDC, under the new leadership of the second Trump administration, moved forward with a study that had previously been shelved.
That framing infuriated mainstream researchers, who saw the trial as a case of ideology overriding established evidence. The controversy also fed into a broader confrontation over the CDC’s direction, as the agency’s vaccine advisory processes came under intense scrutiny.
“We were not given the necessary governmental approval.” — Frederik Schaltz-Buchholzer, lead researcher, in a LinkedIn post announcing the trial would not proceed
Coverage of the halt reflected the sharp split in framing. Outlets such as MSN and Rolling Stone emphasized the political dimension, describing the study as one “championed by RFK Jr.” that was “previously shelved.” The Guardian foregrounded the scientific-ethical backlash, noting the trial “drew global backlash.” Ars Technica, which had reported on the cancellation under the headline that the study was “canceled after international outcry,” underscored the role of the scientific community’s opposition. Across the coverage, the same core facts recurred: a CDC-funded trial, a Danish-led research team, African newborns as subjects, and an abrupt reversal.
Democrats demand answers
The reversal has not quieted the political fight. House Democrats have formally demanded answers from the CDC about how the African hepatitis B study was conceived, reviewed and approved, according to reports — a request that signals congressional oversight is likely to continue even as the trial itself stalls.
Lawmakers are expected to press the agency on several fronts: who inside the CDC authorized funding for the study; what ethics and institutional review processes were followed; how Kennedy’s public advocacy intersected with agency decision-making; and whether the episode has damaged the credibility of US-backed research abroad.
Why it matters beyond one study
- Trust in global health research: Trials conducted in low-income countries depend on local regulatory consent and international ethical consensus. A high-profile collapse can make future collaborations harder to launch.
- African sovereignty in research: The final word came from Guinea-Bissau’s government, whose withheld approval was decisive — a reminder that host-country authorities, not foreign funders, hold the ultimate veto.
- The CDC’s internal turmoil: The episode illustrates how vaccine policy has become a battleground inside the agency, with career scientists publicly at odds with political appointees.
- Hepatitis B and infant mortality: The underlying scientific question about non-specific vaccine effects remains unresolved, and researchers warn it will now be even harder to study.
For the Bandim Health Project, which has operated in Guinea-Bissau for decades, the outcome is a significant setback. For global health agencies, it is a cautionary case about how quickly a technically modest trial can become a geopolitical symbol. And for the communities the study was meant to serve, the immediate consequence is simpler: a trial that would have enrolled their newborns will not happen — at least not under current conditions.
Whether the research question is pursued elsewhere, and with what safeguards, remains unknown. Schaltz-Buchholzer’s statement closed one chapter without opening another, and neither the CDC nor Guinea-Bissau’s health ministry had, as of Wednesday, offered a detailed public account of the decision. Democrats in Congress, meanwhile, appear determined to make sure the record is fully aired.
