A Danish Couple’s Maverick African Research Finds Its Moment in RFK Jr.’s Vaccine Policy

In 1996, Guinea-Bissau seemed like an ideal research post for budding pediatrician Lone Graff Stensballe. Her supervisor, a fellow Dane named Peter Aaby, had spent nearly two decades collecting data on 100,000 people living in the mud brick homes of the West African country’s capital. Aaby and his partner, Christine Stabell Benn, believed that the years of research in the impoverished country had yielded a major discovery about vaccines — and what they described as “non-specific effects”: The measles and tuberculosis vaccines, which were derived from live, weakened viruses and bacteria, they said, boosted child survival beyond protecting against those particular pathogens. But, the scientists said, shots made from deactivated whole germs, or pieces of them, such as the diphtheria-tetanus-pertussis shot, caused more deaths — especially in little girls — than getting no vaccine at all. The World Health Organization repeatedly and inconclusively examined these astonishing findings, which tended to elicit shrugs from the researchers’ colleagues in global health. Then came Donald Trump, covid, and the administrative reign of anti-vaccine advocate Robert F. Kennedy Jr. Suddenly, Aaby and Benn weren’t just sending up distant smoke signals from a far corner of the planet. They were confidently voicing their views and policy prescriptions online and in medical journals. The “framework” for “testing, approving, and regulating vaccines needs to be updated to accommodate non-specific effects,” their team wrote in a 2023 review . And the Trump administration has taken notice. “They became more strident in saying that their findings were real and that the world needed to do something about it,” said Kathryn Edwards, a Vanderbilt University vaccinologist who has been aware of Aaby’s work since the 1990s. “And they became more aligned with RFK.” Kennedy, as secretary of the Department of Health and Human Services, cited one of Aaby’s papers to justify slashing $2.6 billion in U.S. support for Gavi, a global alliance of vaccination initiatives. The cut could result in 1.2 million preventable deaths over five years in the world’s poorest countries, the nonprofit agency has estimated. Kennedy has frozen $600 million in current Gavi funding over largely debunked vaccine safety claims. Kennedy described the 2017 paper as a “landmark study” by “five highly regarded mainstream vaccine experts” that found that girls who received a diphtheria-tetanus-pertussis, or DTP, shot were 10 times as likely as unvaccinated children to die from all causes. In fact, the study was far too small to confidently make such assertions, as Benn later acknowledged. In a study of historical data that included about 500 girls, four of those vaccinated against DTP in a three-month period of infancy died of unrelated causes, while one unvaccinated girl died during that period. A follow-up published by the same group in 2022 found that the DTP shot by itself had no effect on mortality. Critics say the 2017 study, rather than being a landmark, exemplified the troubling shortfalls they perceive in the Danish team’s research. As Aaby and Benn’s U.S. profile has risen, scientists in Denmark have set upon the work of their compatriots. In news and journal articles published over the past 18 months, Danish statisticians and infectious disease experts have said the duo’s methods were unorthodox , even shoddy , and structured to support preconceived views . A national scientific board is investigating their work. Christine Stabell Benn has led a vaccine research project in Guinea-Bissau for nearly three decades with her husband, Peter Aaby. (Thomas Lekfeldt/Ritzau Scanpix/Sipa USA) Stensballe, who worked with Aaby and Benn for 20 years, has been among those voicing doubts. “It took years to see what I see clearly today, that there is a strange concerning pattern in their work,” Stensballe said in a phone interview from Copenhagen, where she treats children at Rigshospitalet, the city’s largest teaching hospital. She said their work is full of confirmation bias — favoring interpretations that fit their hypotheses. Those hypotheses overlap, in important areas, with the notions of Kennedy and other vaccine-skeptical officials at HHS. In December, HHS announced the agency would award the scientists’ Bandim Health Project in Guinea-Bissau $1.6 million to study whether the birth dose of hepatitis B vaccine weakens babies’ immune systems or causes neurological issues. The researchers plan to withhold the vaccine from half of the 14,000 newborns in the study, although the long-established vaccine is 90% effective in preventing infection. The Bandim group justifies this decision by noting that impoverished Guinea-Bissau does not yet routinely vaccinate infants against hepatitis B. Given that 1 in 5 Guinea-Bissauan adults carry the hepatitis B virus, however, the WHO and many infectious disease specialists say it is unethical to withhold the birth dose. Aaby and Benn did not respond to repeated requests for comment. They have vigorously defended their work elsewhere. A Mixed Reputation Many Danes admire the two for their decades of work in Guinea-Bissau, a nation of over 2 million people where, as in much of Africa, infant mortality has plunged over the past five decades. There’s even a novel, the 2013 Danish thriller The Arc of the Swallow , featuring a corporate plot to murder a scientist character clearly based on Aaby. The company’s goal: to keep him from publishing data showing deadly effects from the DTP shot. Benn has said she gave the author the idea for the book. Aaby and Benn have trained around 30 scientists through their Bandim Health Project, named for a district of Bissau, Guinea-Bissau’s capital. The research group has published over 1,000 academic papers and won scientific prizes. The Danish king knighted Benn last year. Their notion of non-specific vaccine effects gained enough traction to merit a short chapter in the 2023 edition of Plotkin’s Vaccines , the authoritative text of vaccinology. Yet Danish health authorities have never followed Aaby and Benn’s vaccine advice. They still offer vaccines based on inactivated viruses and bacteria, on a schedule that Kennedy largely shifted the U.S. to in January. (A federal judge on March 16 temporarily blocked those changes.) Danish vaccine authorities are considering the addition of two of the shots Kennedy sought to drop from the U.S. schedule — against rotavirus and respiratory syncytial virus, or RSV. “What’s important is that Christine doesn’t have influence on our vaccine policy,” said Anders Hviid, chief epidemiologist at Statens Serum Institut, the Danish equivalent of the Centers for Disease Control and Prevention. Hviid — who knows Benn, as do most members of the tiny Danish vaccine fraternity — has contributed to many vaccine safety studies, including a 2019 paper that found no link between measles-mumps-rubella, or MMR, vaccination and autism. Kennedy tried unsuccessfully to get a journal to retract a recent Hviid study showing no link between aluminum-adsorbed vaccines and allergies or neurodevelopmental disorders. In a 2023 podcast with Tracy Beth Høeg, the Danish American sports medicine doctor and covid vaccine skeptic who led the FDA’s drug regulation from December until she was fired on May 15 , Benn said she had vaccinated her son and daughter, now in their late 20s, under the complete Danish schedule of vaccines. Like the U.S. schedule, Denmark’s includes a less reactive form of the DTP shot known as DTaP. Tracy Beth Høeg, a sports medicine doctor and covid vaccine skeptic who emerged as the chief FDA drug regulator under Health and Human Services Secretary Robert F. Kennedy Jr., takes part in an Advisory Committee on Immunization Practices hearing in Atlanta in December. She was fired on May 15. (Megan Varner/Bloomberg via Getty Images) These vaccines aren’t dangerous to kids in well-off countries like the U.S. and Denmark, she said. But she said she would “never vaccinate my child according to the U.S. program.” She singled out the hepatitis B vaccine birth dose, which her group plans to test in Guinea-Bissau, saying she was “appalled” that the CDC recommended a universal birth dose. Kennedy’s handpicked vaccine advisory committee — which a federal judge in March cast into limbo , questioning its members’ qualifications — withdrew the birth dose recommendation last year. Compatriots Grow Skeptical Kennedy’s championing of Aaby and Benn prompted criticism from Danish scientists that has extended to the ethics of the hepatitis B study . “It is disturbing that Danish researchers could carry out such actions involving African children,” Stensballe said. As of early March, the study was paused while officials from Guinea-Bissau and the African Centers for Disease Control examined it. Public Health Minister Quinhin Nantote, who took office after a November coup in Guinea-Bissau, said in January he had no evidence that the six-member ethics committee that signed off on the study earlier had ever met to discuss it. HHS spokesperson Andrew Nixon told KFF Health News the proposed study was “based on the highest scientific and ethical standards” and “represents the world’s first and perhaps only opportunity to test the overall health effects” of the hepatitis B vaccine. It’s only one area of the couple’s research that is under scrutiny. In 2024, Danish physician and journalist Charlotte Strøm published an article noting that the Bandim group scientists had failed to publish data they’d collected that contradicted their frequent claims that the vaccine c…