Danish researchers planned a United States-funded vaccine trial in Guinea-Bissau that sparked public and professional outrage and was suspended by the government on January 22 pending review.
The study proposed enrolling 14,000 newborns to compare health outcomes over five years between two groups: half randomly assigned to receive the hepatitis B vaccine at birth (the WHO-recommended timing) and the other half to receive the vaccine six weeks later, the schedule commonly used in Guinea-Bissau because of limited supply. The researchers said the trial would take advantage of a planned national shift to at-birth vaccinations in 2028 and would mean that roughly 7,000 infants would receive at-birth vaccination for the first time in the country.
Critics argued the study was unethical because it delayed a proven, life-saving intervention for infants at highest risk of chronic hepatitis B virus (HBV) infection. Babies infected at birth face far higher risks of long-term liver disease and cancer. “It is unethical to deny children an intervention that we know works,” former Guinea-Bissau health minister Magda Robalo told Al Jazeera, saying national public health authorities had not been fully informed and that researchers had taken advantage of the country’s limited research capacity.
The Bandim Health Project, based in Guinea-Bissau and affiliated with the University of Southern Denmark, would lead the trial. It is chaired by Christine Stabell Benn and was founded by Peter Aaby, who have long investigated “non-specific” effects of vaccines — unintended impacts beyond the targeted disease. Some of their past work suggested certain inactivated vaccines, such as DTP (diphtheria, tetanus, pertussis), might be linked to higher child mortality in specific contexts, particularly among girls. Those findings prompted WHO review but were judged inconsistent, and WHO has continued to recommend DTP vaccination.
The pair and their collaborators say their research aims to reveal both beneficial and harmful unintended effects. But critics accuse them of overreaching, noting repeated null findings they say the researchers have ignored. A Danish investigation reported the pair did not publish results of a randomized controlled trial (RCT) on DTP conducted 14 years earlier; the trial later appeared on a preprint server after media scrutiny. Defenders note an institutional review found no grounds for sanctions.
Researchers including Anders Peter Hviid of the Danish State Serum Institute questioned why investigators who claim inactivated vaccines can harm children would proceed to administer those vaccines in trials. Other scientific criticisms addressed the trial design: it was planned as an open-label RCT, meaning investigators would know which infants received which schedule, potentially introducing bias, and the five-year follow-up may be too short to capture hepatitis B outcomes that can appear much later in life.
The trial gained funding in December when the US Centers for Disease Control (CDC) awarded a $1.6m grant without a competitive process, according to public records. The CDC under Health Secretary Robert F. Kennedy Jr — a vaccine sceptic whose tenure has included dismantling parts of the agency’s scientific leadership — has changed US vaccine policy and funding priorities. The US health department has reduced the number of vaccines it recommends for newborns and removed a long-standing recommendation that hepatitis B vaccines be given at birth, leaving the decision to guardians and clinicians. The Bandim project’s work was cited by US officials when cutting funding to Gavi, the Vaccine Alliance.
Leaked protocol details published online showed the Guinea-Bissau study would investigate whether giving the hepatitis B vaccine at birth could be linked to skin disorders or neurodevelopmental conditions such as autism by age five — a claim that echoes vaccine-safety narratives promoted by some anti-vaccine advocates. WHO and other major bodies say there is no link between vaccines and autism.
After the trial attracted attention, Guinea-Bissau sought review from the Africa Centres for Disease Control and Prevention. The country’s new government, installed after a November military coup, said its health ministry had not been involved in discussions about the study. The new health minister confirmed the government had not approved the trial.
The controversy echoes painful episodes in medical research history where vulnerable populations were exposed to harmful or unproven interventions without proper consent or oversight. Critics pointed to past cases — the 1996 Trovan antibiotic trial in Nigeria that caused severe harm to children, and the Tuskegee syphilis study in the United States, in which Black men were observed without treatment for decades — as reasons for heightened caution and community mistrust.
In Guinea-Bissau, where roughly one in five people is estimated to carry HBV, public health experts and former officials argued the priority should be securing adequate vaccine supply so all infants can receive the birth dose now, rather than using newborns as subjects for a trial. Robalo said the Bandim researchers, who have worked in the country for decades, should have engaged national institutions and helped build local research capacity, particularly after political upheaval. “We are not a population to be used for anything that you cannot do in the Global North. We demand respect,” she said.
Bandim researchers defended the study, saying they would not withhold vaccines from children who otherwise would have received them and that the trial would expand access for some infants. They criticized critics for moral outrage and urged a “curious and humble” scientific approach. The debate highlights tensions over research ethics, global health power dynamics, scientific uncertainty about non-specific vaccine effects, and how international funders and local authorities should navigate trials involving vulnerable populations.
