This article is made possible through Spotlight PA’s partnership with NOTUS, a nonpartisan news organization that covers government and politics with the fresh eyes of early career journalists and the expertise of veteran reporters.
The Trump administration has repeatedly cited a paper that was never formally peer-reviewed in justifying its cuts to the childhood vaccine schedule and calling for new studies into already-approved vaccines.
Leading vaccine researchers tell NOTUS that the paper proposes flawed research studies that could lead to meaningless data and unreliable conclusions.
The Department of Health and Human Services, under Robert F. Kennedy Jr.’s leadership, called for “more and better science, including gold standard placebo-controlled randomized trials” on vaccines in a January assessment of the childhood vaccine schedule written by two HHS officials, Martin Kulldorff and Tracy Beth Høeg.
In that assessment, the administration repeatedly referenced a paper authored last year by a Danish researcher affiliated with the “Make America Healthy Again” movement, Christine Stabell Benn, and Kulldorff, titled “Proposals for Post-Market Randomized Childhood Vaccine Trials with Ethical Designs.”
That paper, which was published without being evaluated for quality, validity or methodology by other scientists, proposes nine trials.
All of the proposed trials are focused on vaccines that have already been approved by the Food and Drug Administration. All would be placebo-controlled, meaning some children participating would not receive any vaccine — a normal practice for testing vaccines against new diseases, but not for diseases for which there is already a tested vaccine, like the flu or hepatitis B.
Five experts, including a vaccine inventor and a former FDA official, resoundingly disagreed with the paper’s suggestions in interviews with NOTUS.
“I think you would end up with results that would be very hard to interpret,” said Susan Ellenberg, a professor emerita of biostatistics, medical ethics and health policy at the University of Pennsylvania. “When you ask enough questions, you are going to find some things that are statistically significant by chance.”
That could make it easy to use the study results to argue that vaccines cause effects that in reality are extremely rare, Ellenberg said.
“I worry that they will jump on whatever they find as truth when it’s not reliable,” she added.
An HHS spokesperson declined to comment on whether the department was planning to conduct any of Benn and Kulldorff’s proposed trials.
But Benn’s research group recently received a grant from the Centers for Disease Control and Prevention to conduct a study on the safety and efficacy of the hepatitis B vaccine birth dose in children in Western Africa — which is also the first study proposed in the paper she co-authored with Kulldorff.
Public health experts have decried that study, which would give some infants in Guinea-Bissau the hepatitis B vaccine at birth, and others at six weeks of age (the timing the country currently recommends), as unethical.
The status of that study is now unclear. The Ministry of Health of Guinea-Bissau said last month that their ethics committee would rereview the study before it begins; an HHS spokesperson told NOTUS they were confident the study would proceed. Benn did not respond to a request for comment about her involvement in further studies.
One former employee of the National Institutes of Health involved in study design said that while they’d looked over Benn and Kulldorff’s paper when it was published last year, they hadn’t been involved in any discussion about actually conducting the studies.
The January vaccine schedule assessment was not the first time the MAHA movement has proposed conducting more studies on already-approved vaccines.
Kennedy has repeatedly called for further research into vaccine side effects and efficacy. The Washington Post reported last year that HHS would require new vaccines to be tested against placebos.
Public health experts say such a trial could risk being unethical if it withholds a known treatment from patients.
Paul Offit, who co-invented a rotavirus vaccine and now directs the Vaccine Education Center at the Children’s Hospital of Philadelphia, said he thought all of the studies proposed by Benn and Kulldorff’s “ethical designs” paper were unethical.
“I don’t think you can do unethical studies,” Offit said. “You can’t do a no-flu vaccine study, because let’s suppose you find out that the flu vaccine is effective, which I think we’ve known since the 1940s. How are you explaining that to the parents of the child who’s in the placebo group?”
Michael Osterholm, the director of the Center for Infectious Disease Research at the University of Minnesota, said the proposal “rivaled what we did at Tuskegee,” referring to the Tuskegee Syphilis Study, in which hundreds of Black men with syphilis were intentionally not offered available treatments.
“Withholding vaccine from these kids to do these kinds of studies is unconscionable,” Osterholm said.
Many of the other trials the paper proposes — including those comparing the timing of the measles, mumps and rubella vaccine, looking at the amount of aluminum in vaccines, comparing the Danish and U.S. vaccine schedules and giving some children the influenza vaccine, but not others — align with the arguments used by the MAHA movement when sowing doubt on whether vaccines are as important and effective as the vast majority of public health experts say they are.
Those experts, the paper argues, should also be in favor of the proposed trials.
“People, who are convinced that vaccines are safe and effective, should welcome these trials as they will prove them right if they are right,” it states.
Ellenberg and other experts in scientific study design disagreed. The way the proposal attempts to answer multiple questions about vaccines within a single study, they said, could make it extremely difficult to parse out what the unintended effects of each vaccine are — or if they even have any.
“It would be really unusual at FDA” to rely on such a study to make a major public health decision, according to Jesse Goodman, a professor of medicine at Georgetown University who served as chief scientist of the Food and Drug Administration from 2009 to 2014.
Kulldorff has been behind several controversial decisions at HHS. A Swedish biostatistician, he became one of the loudest scientific voices speaking out against vaccine mandates during the COVID-19 pandemic, and said he was fired from his professorship at Harvard University in 2024 after refusing to get vaccinated against COVID-19.
In June, Kennedy appointed Kulldorff to the CDC’s Advisory Committee on Immunization Practices. After serving as the committee’s chair for several months, during which the ACIP voted to no longer recommend a combination shot that protects against chickenpox as well as measles, mumps and rubella, he stepped down to become the chief science officer for the Office of the Assistant Secretary for Planning and Evaluation.
“Martin Kulldorff transformed ACIP from a rubber stamp into a committee that delivers gold-standard science for the American people,” Kennedy said in a statement announcing Kulldorff’s new role.
Kulldorff did not respond to a request for comment from NOTUS.
ASPE, where Kulldorff now works, provides policy advice to the health secretary and “coordinates department-wide research and evaluation activities,” according to Kennedy’s statement.
It would be unusual, but not unheard of, for HHS to fund — or even conduct — further research on medical products like vaccines that have already been approved by the FDA and have been in use for decades.
But a complex study with many different variables like the one proposed by Benn and Kulldorff would require a vast number of participants, making it extremely expensive, said William Moss, a professor at Johns Hopkins University and executive director of the International Vaccine Access Center. Benn and Kulldorff propose conducting a study looking at different vaccines on over 100,000 children over a period of several years.
“This would be a major historical undertaking,” Moss said. Large, yearslong clinical trials can cost hundreds of millions of dollars to conduct.
It’s not clear at this point whether HHS actually will. While the department has announced other new initiatives related to the MAHA movement’s views on vaccines — appointing a new Interagency Autism Coordinating Committee to “support breakthrough innovations in autism research, diagnosis, treatment, and prevention,” for instance — the hepatitis B study in Guinea-Bissau is the only new research on vaccines HHS has funded so far.
And until that changes?
“Until more studies are completed, the childhood vaccination recommendations must be based on the best available evidence, however limited,” Kulldorff and Høeg wrote in their assessment.