Health Secretary Robert F. Kennedy Jr. on Thursday announced plans to require all new vaccines to be tested against placebos and to develop new vaccines without using mRNA technology, moves that extend his reach deep into vaccine development and raise questions about whether Covid boosters will be available in the fall.
A spokesman for the Department of Health and Human Services called the requirement for placebo testing “a radical departure” from existing standards. But that will depend on how the department defines “new,” because most new vaccines are already tested either against placebos — inert substances — or, in some cases, against vaccines for other diseases.
Mr. Kennedy is one of the nation’s leading vaccine skeptics, and he has been vocal about his disdain for mRNA technology, which was used to develop coronavirus vaccines during the first Trump administration. He once wrote on social media that “mRNA jabs don’t stop infection, don’t block transmission, don’t block mutants, don’t last, don’t work at all.”
Mr. Kennedy’s activism in recent years included petitioning the Food and Drug Administration to pull the Covid vaccine off the market in 2021, during a deadly phase of the pandemic. He also urged the F.D.A. not to authorize Covid shots for children. Mr. Kennedy has also maintained that there could be a link between vaccines and autism, and hired a discredited researcher into his agency whose work aligns with that view.
Since becoming health secretary in February, Mr. Kennedy has made few high-profile pronouncements on vaccine policy, with the exception of his tepid endorsement of the measles shots in response to the outbreak in Texas that has killed two children and one adult. But he and the Trump administration have waded into the issue in other ways, by ordering a study on vaccines and autism and delaying approval of another Covid vaccine.
Mr. Kennedy’s announcements on Thursday represent an extraordinary use of his power as secretary to make decisions ordinarily left to career scientists at the F.D.A. The moves follow his recent instructions that parents of newborns considering vaccination should “do your own research.”
Mr. Kennedy has said he intends to restore trust in the vaccine approval process, but Dr. Jesse Goodman, a former F.D.A. official and an infectious diseases doctor at Georgetown University, said the changes could erode trust.
“Questions never bother me,” Dr. Goodman said, “but it’s really worrisome when it seems like they’re so ubiquitous and so constant that they sow a huge amount of doubt — not just about the one thing, but about everything.”
Most immediately, Mr. Kennedy’s move could affect the next round of Covid booster shots, expected to become available in the fall. Both flu shots and Covid boosters have been authorized without extensive human trials to target new strains of the virus as it has evolved.
Mr. Kennedy says the new policy will not affect flu shots, but the future of Covid boosters is now in doubt. Andrew Nixon, the department spokesman, said that because so many people have been infected and now have immunity to Covid, new studies are required.
“As we’ve said before, trials from four years ago conducted in people without natural immunity no longer suffice,” he said. “A four-year-old trial is also not a blank check for new vaccines each year without clinical trial data, unlike the flu shot, which has been tried and tested for more than 80 years. The public deserves transparency and gold-standard science — especially with evolving products.”
Mr. Kennedy’s plan for the placebo studies, first reported by The Washington Post, also raises ethical questions. It is considered unethical to deprive even a small group of patients of effective vaccines against deadly pathogens. In the case of Covid-19, new clinical studies could hold up authorization for boosters, which would leave the entire U.S. population vulnerable.
Dr. Ofer Levy, a Harvard vaccine researcher and a member of the F.D.A.’s vaccine advisory committee, said that would be “unacceptable,” and that officials must “thread the needle” to be sure the studies are done in a way that do not leave older and immunocompromised people unprotected from Covid.
“Tens of thousands of people can die without protection against Covid,” said Dr. Levy, who co-founded a company working on an opioid vaccine.
The Centers for Disease Control and Prevention reported about 23,000 deaths from Covid since September, with as many as 1,000 a week that month and in January. Still, uptake of the Covid boosters has been low: About 23 percent of adults got the updated Covid shot released in the fall, according to the C.D.C.
One C.D.C. study of the Covid boosters used in 2023 and 2024 found that they averted about 68,000 hospital stays, and were most effective in people who were older than 65 or immunocompromised.
The health secretary’s familiarity with vaccine trials stems at least in part from his reviews of decades-old vaccine approvals, including for the polio vaccine and the measles, mumps and rubella vaccine. Mr. Kennedy has also helped represent plaintiffs in lawsuits against manufacturers.
He and the organization he founded and once led, Children’s Health Defense, have repeatedly complained that vaccines are not tested against placebos in clinical trials when they are being developed. The organization has cited polio, hepatitis and meningitis vaccines as examples, all of which were introduced decades ago.
“Every other medicine is tested against a placebo,” Mr. Kennedy said on a podcast in January 2020, in claiming that vaccines are exempt from that requirement.
That, however, is not entirely correct. Cancer drugs and other medications authorized under the F.D.A.’s accelerated approval program are regularly authorized after trials without a placebo. And new vaccines, including the vaccines for Covid, were tested against placebos — inert substances, such as a saline injection, or in some cases against vaccines for other diseases.
“We’ve required placebo-controlled trials for most vaccines, and sometimes it’s an inert placebo, and sometimes it’s an irrelevant vaccine,” said Dr. Peter Marks, who was the Food and Drug Administration’s top vaccine official until he was forced out in March. “The claim that we have not done randomized trials for pediatric vaccines aside from Covid is not correct.”
Mr. Kennedy has also raised concerns in the past about testing a vaccine against what many scientists consider a reasonable placebo: the same formula, but without the immune-activating agents. Mr. Kennedy has noted that the practice leaves uncertainty about whether ingredients in the formula could cause harm.
In addition to the new placebo requirement, Mr. Kennedy also announced a National Institutes of Health initiative to turbocharge the development of new inoculations for Covid, bird flu and seasonal flu — an effort that appears to be part of a broader assault on mRNA technology, or “platform.”
Since they were developed, Mr. Kennedy issued numerous social media posts about the mRNA shots, including one positing that the F.D.A.’s assessment of the Moderna shot for children in 2022 was “dishonest, and evidence that the public health establishment has abandoned science, logic, reason, rationality, empathy, health and medicine.”
The N.I.H. under the Trump administration has subjected studies related to the mRNA platform to strict scrutiny. Bills restricting the use of mRNA vaccines have popped up in Republican-controlled state legislatures, including in Texas, Idaho and Kentucky.
The F.D.A. is also holding up approvals of a Covid vaccine that is not based on mRNA technology.
The agency was expected to issue a decision on April 1 regarding whether to issue a full approval of the more traditional protein-based Novavax Covid shot, which had been used under emergency authorization. The F.D.A. delayed the decision, though, asking the company to conduct additional research.
“I’m curious if this administration actually intends to just obliterate the Covid vaccine,” said Richard Hughes, a lawyer with the law firm Epstein Becker Green who represents some vaccine makers.
Pfizer and Moderna, makers of the mRNA Covid shots, did not respond to questions about whether updated shots will be available in the fall in the United States.
A spokesman for Moderna said the company has run clinical trials for its booster shots before and after their launch. During an earnings call Thursday, president Stephen Hoge said the company tests its vaccines against placebos. A policy change had not been communicated to the company directly, he said, but “we will absolutely engage constructively and making sure we understand what those needs are and that we fulfill them.”
The new N.I.H. initiative, meanwhile, would develop a “next-generation vaccine platform” that would be “fully government-owned,” the department said. The N.I.H. helped develop the mRNA platform, and the vaccine maker Moderna paid the government hundreds of millions of dollars to license a key patent on the vaccine, though the company and the government later got into a dispute over the patent rights.
The mRNA platform relies on small bits of genetic code, which generated online rumors and conspiracy theories that it was being used to insert microchips into vaccine recipients. The new platform, by contrast, would rely on a more traditional method of vaccine development, which uses inactivated viruses to provoke an immune response.
The department said the new platform would be developed using beta-Propilactone, which is already a component in vaccine development but is considered a hazardous substance by the Environmental Protection Agency when people are exposed to it in large doses.
