Last week, Health and Human Services Secretary Robert F. Kennedy Jr. made a pronouncement that stunned the global health world.
Gavi, the Vaccine Alliance — which has vaccinated more than half the world's children in many of the world's lowest-income countries — was hosting a major event to solicit donations for its global vaccination efforts. RFK Jr. decided to take the opposite stance. He said the U.S. would cut off more than a billion dollars that had previously been promised over the next few years. In a video, he slammed Gavi, saying "it has neglected the key issue of vaccine safety."
His evidence: A study from 2017.
This study looked at children in the west African country of Guinea-Bissau who had been given the DTP vaccine — for diphtheria, tetanus and pertussis, three potentially fatal diseases.
Although DTP vaccines have been credited with saving over 40 million lives globally, the study claimed that children who received the vaccine were more likely to die than other children who had not yet received it.
What do we know about the study that RFK Jr. cited? And does it make a convincing case that Gavi has indeed neglected safety issues? To answer these questions, NPR interviewed top vaccine researchers — including some tasked with looking at the very issue raised by this study about the safety of the DTP vaccine.
What to know about the 2017 study?
The 2017 study was published in the peer-reviewed journal eBioMedicine, which is part of The Lancet, a highly regarded medical publication. The researchers looked at just over 1,000 children who received the DTP vaccine in the early 1980s.
The issue is not whether the DTP vaccine works. It is universally acknowledged to be highly effective at preventing these three deadly diseases.
Instead, the researchers behind the 2017 study were fascinated by a different issue: Did the DTP vaccine cause children to get sick and die from other causes?
Their study looked at infants between 3 and 6 months. It claimed that children who got the DTP vaccine — as well as the oral polio vaccine — around the age of 3 months were five times more likely to die before they turned 6 months compared to infants that had not yet received their vaccines. According to the study, of these children a few died of respiratory issues, a few of fever, a handful of diarrhea. Still others died of unknown causes.
RFK Jr. called the 2017 report a "landmark study" by "five internationally revered deities of vaccine research, all of whom are strong vaccine proponents."
Four are researchers in Denmark and the other is from Guinea-Bissau. Dr. Christine Stabell Benn and Dr. Peter Aaby — who is also an anthropologist — are the two authors who have published on this topic over the past 25 years. They did not respond to NPR's requests for interviews.
Vaccine experts interviewed by NPR point to several problems with the study:
First: The data is old — really old
While the study was published less than a decade ago, the data it relies on is from the early 1980s — more than 40 years ago.
"The study is based on ancient data," says Dr. Beate Kampmann, a vaccinologist and pediatrician who is the scientific director of the Centre for Global Health at Charité, Universitätsmedizin Berlin — one of Europe's largest university hospitals.
"During that time, vaccines were not commonly used in the country, and the risk of death in infants was extremely high," explains Dr. Kate O'Brien, the director of the Department of Immunizations, Vaccines and Biologicals at WHO.
Since then, the number of youngsters who die has dropped precipitously.
According to data from the World Bank, in 1984 in Guinea-Bissau, 244 kids died before their fifth birthday out of every 1,000 kids born. In 2023, that number had dropped to 69.
O'Brien says this means any findings from back then aren't very applicable to today's world.
Second: Two of the key researchers later came out with a different finding
Stabell Benn and Aaby — who published the 2017 paper — published another paper in 2022. It looked at the same west African country and the same vaccine but the data was more recent. This time their data was gathered between 2010 and 2014. And, in this study, they found "no effects on all-cause mortality" for kids who got the DTP vaccine compared to those who got it later.
NPR sent Health and Human Services a detailed list of questions about this study — as well as all the other concerns outside experts raised with the 2017 study. The HHS spokesperson did not respond to the specific questions but sent a statement via email reiterating what RFK Jr said in his video.
"Secretary Kennedy believes that global public health recommendations must not rely on assurances alone, but on continuous, independent review and rigorous debate," read part of the statement.
Third: The study methods are not ideal
Outside researchers who have looked at the 2017 study say there are a lot of gaps in the information provided in the study and that the methodology is challenging to understand.
The gold-standard in research is a randomized controlled trial, where study participants are randomly assigned to get the vaccine or get a placebo. That didn't happen here. Instead, the researchers simply observed what happened naturally.
This approach is problematic, says Dr. Paul Offit, the director of the Vaccine Education Center at the Children's Hospital of Philadelphia and previously a member of the Advisory Committee on Immunization Practices to the Centers for Disease Control and Prevention. He says you can imagine parents might seek out the vaccine if their kids seemed sickly. But perhaps if they were more sickly, they were more likely to die anyway.
"You have to control for things like socioeconomic background, medical background, health care seeking behavior — this study didn't control for those things," he says.
Also, Offit says, researchers usually put forward an explanation about how the vaccine might be causing these deaths. But, he says, the authors of this study did not offer any theories. "What is your proposed mechanism?" he asks.
Several outside experts said they had a very hard time understanding what the researchers actually did and how the data was analyzed. "[The] statistical methods are all over the place," says Kampmann.
While author Stabell Benn did not respond to NPR's requests for an interview, in a 2019 TEDx Talk, she said, her results haven't been accepted by the medical community. "I've spent literally years, I think, pulling out my hair and speculating why it's so difficult." She blames the polarized vaccine debate, saying both sides don't want to consider data that runs counter to their stance.
Fourth: Today's vaccines are different
Outside vaccine experts say it's important to note that the DTP vaccine that was given in the 1980s — and was in use during the data-gathering for 2017 study RFK Jr. cites — is not the same as the current version.
Today's DTP vaccines "are made in a completely different way," says Kampmann, explaining that the pentavalent vaccine is widely used. This vaccine not only protects against diphtheria, tetanus and pertussis but also hepatitis B and Haemophilus influenzae type b. So any possible consequences from that older vaccine would not be relevant today, she says.
Fifth: "If there was a problem, we would probably know it"
The researchers who did the 2017 study raised their concerns about the DTP vaccine as early as 2000. Since then, outside experts have been looking into the issue and reassessing all the data.
The Global Advisory Committee on Vaccine Safety — which was established by the World Health Organization but operates independent of WHO — urged WHO to test this DTP vaccine by looking at data gathered in other countries. Studies were conducted in Bangladesh, Burkina Faso, Indonesia and Papua New Guinea. By 2002 the studies were complete, and the conclusion was in.
"The studies showed no negative effect of DTP vaccination," according to a report of the GACVS's June meeting published in the WHO Weekly Epidemiological Record on November 22, 2002.
GACVS has a special task force look at the issue, reporting back in 2004, that DTP helped child survival and did not hurt it. It was again considered in 2008 and then, in 2014, the Strategic Advisory Group of Experts on Immunization (SAGE) — a group of independent experts that advises the WHO — took it up.
The 2017 study author, Stabell Benn, was on this SAGE panel of experts, as was O'Brien who is now at WHO. The experts looked at all the studies on this question of DTP causing unrelated health consequences. Almost half the studies they looked at were from the Guinea Bissau team. These study results were mixed — some found a negative effect and others did not — but what was consistent, the SAGE team found, was that the studies had "significant methodological limitations."
O'Brien says these groups kept reevaluating the data because they were open to new information but the conclusion kept being the same.
"We have billions of people who have been vaccinated [with a DTP-containing vaccine] ... For decades, generations, people have been receiving this vaccine. If there was a problem, we would probably know it right?" she said. "If we step back from vaccination, we will cause harm. It will result in deaths."
"People like Kennedy then put their little poker in and pull out the very specific study that suits their agenda," says Kampmann, noting the RFK Jr. has spread inaccurate information about vaccines in the past.
The aftermath of the RFK Jr. announcement
RFK Jr. said that all financial contributions to Gavi would be paused and the organization needs "to re-earn public trust."
Global health specialists say the consequences of this decision could be huge.
"Of all the global health programs that have been cut, this will likely mean more deaths than any [other cut]," said Dr. Atul Gawande, who oversaw global health work for the U.S. Agency for International Development under President Biden, in an email to NPR.
"It's just a travesty," says Offit from the Children's Hospital of Philadelphia. "There is probably no better public health organization, more effective public health organization, and, frankly, more economical public health organization than Gavi."
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