In justifying the government’s termination of $500 million in funding for mRNA vaccine projects, Health and Human Services Secretary Robert F. Kennedy Jr. falsely claimed mRNA vaccines “fail to protect effectively” against COVID-19 and suggested they are unsafe. The mRNA shots saved millions of lives during the COVID-19 pandemic and have shown promise against influenza.
The projects had been funded by HHS’ Biomedical Advanced Research and Development Authority, which is tasked with preparing the U.S. for public health emergencies such as pandemics. HHS announced that BARDA also would not be funding any new vaccine projects that use mRNA technology.
“We reviewed the science, listened to the experts, and acted. BARDA is terminating 22 mRNA vaccine development investments because the data show these vaccines fail to protect effectively against upper respiratory infections like COVID and flu,” Kennedy said in an Aug. 5 press release. “We’re shifting that funding toward safer, broader vaccine platforms that remain effective even as viruses mutate.”
It is unclear which studies or experts Kennedy is citing, but his claims are contradicted by the peer-reviewed scientific literature and are counter to many experts. The mRNA COVID-19 vaccines have been used widely around the world, and studies have repeatedly demonstrated their effectiveness and safety. Moreover, the mRNA vaccines, which can easily be updated to target new virus variants, have continued to provide protection even as the virus mutates.
Kennedy’s claim about the ineffectiveness of mRNA vaccines is “simply not true,” Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told us. “We have ample data showing major reductions in serious illness, hospitalizations and deaths even after the virus variants have changed some,” he said.
Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital and dean of the National School of Tropical Medicine at Baylor College of Medicine, told us the HHS announcement is “an exercise in disinformation.”
Contrary to Kennedy’s claims, the mRNA COVID-19 vaccines “perform extremely well,” Hotez said, referring to the Pfizer/BioNTech and Moderna vaccines.
Influenza vaccines using mRNA technology also are in development and have shown promise both against seasonal flu and viruses that could cause a pandemic. BARDA had in May canceled $766 million in funding to Moderna for development of mRNA vaccines against bird flu.
Kennedy suggested BARDA would instead invest in “safer” technologies, but mRNA vaccines against COVID-19 have been tested extensively, and serious side effects are very rare.
Experts warned that the decision could leave the U.S. without a way to get an adequate supply of vaccines quickly in the event of a pandemic. A major strength of mRNA vaccines is the speed with which they can be produced.
“In my 50 years in public health and dealing with a number of very challenging public health problems, I’ve never seen a more misguided and even dangerous decision,” Osterholm said.
Dr. Drew Weissman, director of the Institute for RNA Innovation at the University of Pennsylvania, told us in a phone interview that this decision by HHS was “crippling our science for decades to come.”
Weissman and Katalin Karikó won the 2023 Nobel Prize in medicine for their discoveries in 2005 that facilitated the development of mRNA COVID-19 vaccines. While HHS’ decision applies to vaccines for respiratory viruses, Weissman sees a larger impact.
The technology “has enormous potential,” he said, explaining that government funding is what most researchers use to begin their work — and now the Trump administration is “killing the technology in the United States.” The rest of the world will “very soon, pull way ahead of us” in developing mRNA therapeutics. “We’re going to lose all of our young scientists who are going to go overseas to do this work.”
When asked about Kennedy’s decision on Aug. 6, President Donald Trump touted Operation Warp Speed, the federal government’s effort — launched by Trump’s first administration — to support the development of COVID-19 vaccines and quickly deliver them to the public. It was “considered one of the most incredible things ever done in this country,” he said. But, he added, “that was now a long time ago and we’re on to other things, but we are speaking about it,” saying he had a meeting the following day about the issue.
We reached out to HHS with various questions, including asking for support for Kennedy’s scientific claims and for more detail on the vaccine platforms HHS will now invest in, but we did not receive a response.
Data Demonstrate mRNA COVID-19 Vaccine Effectiveness
There have been many studies showing that the mRNA COVID-19 vaccines are effective in preventing symptomatic disease, particularly in preventing severe disease – even as new variants of the virus have emerged.
“The goal is to keep you out of the hospital, keep you out of the intensive care unit and keep you out of the morgue, and this vaccine performs very well in that regard,” Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, told us.
One study, led by researchers at the Yale School of Public Health, estimated that COVID-19 vaccines prevented more than 3 million deaths in the U.S. in the first two years alone. The vast majority of Americans received mRNA vaccines.
The clinical trials for both the Moderna and Pfizer/BioNTech mRNA vaccines showed that two doses were more than 90% effective in preventing symptomatic and severe COVID-19. Protection against infection and mild disease waned over time and with the emergence of new variants, but many studies continued to show the vaccines, which have been updated every year to better target new variants, worked well in preventing severe disease and death. One Centers for Disease Control and Prevention study, published in March 2022, found a 90% risk reduction for invasive mechanical ventilation or death due to COVID-19 for people who received two or three mRNA doses, compared with those who had not gotten any doses.
As time has passed, more people in the population have built immunity to COVID-19 through some combination of vaccination and infection. But getting additional shots has continued to reduce the risk of disease.
Most recently, CDC data presented at the June meeting of the agency’s Advisory Committee on Immunization Practices showed the 2024-2025 updated vaccines were “effective in preventing hospitalizations and critical outcomes from COVID-19 in adults,” according to a summary slide.
According to the unpublished data, seven to 179 days after vaccination, the 2024-2025 vaccines reduced the risk of an emergency room or urgent care visit by 34% for adults and by higher percentages for kids, compared with those who didn’t get the updated vaccine. The CDC data also showed the vaccines reduced the risk of hospitalization and critical illness by about 45% for adults age 65 and older without immunocompromised conditions.
Those figures show an added benefit of updated vaccines in an overall population with high levels of immunity from both vaccines and infections.
Research also indicates vaccination likely reduces the risk of long COVID.
Kennedy did not define what he means by “protect effectively,” but if he thinks the vaccines need to prevent viral infection to be effective, that is an inappropriately high bar for a vaccine. As we’ve explained before, most vaccines do not prevent infection entirely, but they can prevent or lessen the severity of disease.
False Claims on the Impact of Variants
Kennedy also vastly overstated the impact of viral evolution on mRNA vaccine effectiveness. “One mutation, and the vaccine becomes ineffective,” he said in a video posted on X.
“That’s flat out wrong,” Hotez said. In no case has a single mutation rendered the mRNA COVID-19 vaccines ineffective.
It’s taken numerous mutations for the effectiveness of the COVID-19 vaccines to decline against a new variant — but even then, the vaccine still provides some protection against severe disease. By the time updated COVID-19 vaccines come out each year, Offit noted, “the strain that was picked has already started to mutate away, and yet — still — the vaccine is effective at preventing serious illness.”
Of course, the more closely the vaccine can match the circulating variants, the better the protection, particularly for mild disease. And indeed, this is why the vaccines are regularly updated. This is an area in which mRNA vaccines excel, since they can be updated more quickly than traditional vaccine platforms.
Moreover, while Kennedy casts this issue as unique to mRNA vaccines — claiming that it’s because they only target a single part of a pathogen — that’s also not true. Novavax’s protein-based COVID-19 vaccine also only targets a single part of the virus.
Kennedy also wrongly suggested that “the vaccine paradoxically encourages new mutations and can actually prolong pandemics.”
Offit said that multiple coronavirus variants arose and became dominant during the COVID-19 pandemic even before vaccines were available. “This virus mutates away from, to some extent, antibody recognition, but it doesn’t need the vaccine’s help to do that,” he said.
“The idea that it [the vaccine] drives the potential for mutations is simply not true,” Osterholm said.
Kennedy Misleads on mRNA Vaccine Safety
Kennedy also misled on the safety of mRNA vaccines. “After reviewing the science and consulting top experts at [the National Institutes of Health and Food and Drug Administration], HHS has determined that mRNA technology poses more risk than benefits for these respiratory viruses,” he said in his video on X.
The mRNA COVID-19 vaccines have been used around the world, and the vaccine side effects identified have been either mild or rare. Year after year, experts advising the CDC have concluded the benefits of vaccination outweigh the risks. Common side effects, such as arm soreness or fever, are short-lived.
“The notion that this vaccine is more dangerous than the virus is just fanciful,” Offit said.
Weissman told us: “The RNA vaccines are the most tested vaccine ever. They are the safest and they’re the most effective. That’s why RNA was used around the world.”
As we’ve written previously, COVID-19 vaccines in rare cases can cause myocarditis and pericarditis, or inflammation of the heart muscle and lining, respectively. But these side effects are not uniquely caused by mRNA vaccines. Myocarditis can also occur rarely after the protein-based Novavax vaccine. Cases of myocarditis after getting COVID-19 tend to be more severe than cases following vaccination. Moreover, vaccine safety monitoring has not shown a link between COVID-19 vaccination and myocarditis in the past three years of data.
In his video, Kennedy said that HHS would invest in “safer” technologies including “whole-virus vaccines and novel platforms that don’t collapse when viruses mutate.” In May, HHS had announced it was investing in an inactivated whole-virus vaccine platform being developed by in-house NIH scientists who hold leadership roles at the agency.
But experts have disputed the notion that vaccines using this platform will be safer or more effective than alternatives. “There are many of us who have spent an entire career working on flu vaccines that would tell you that the work that the NIH is now promoting … we have many concerns about,” Osterholm said. He added that it is an old technology evaluated many years ago and “was not shown to be effective at that time.”
Moreover, whole-pathogen vaccines can cause more side effects than alternatives.
Hotez also disputed Kennedy’s claim that HHS is “prioritizing the development of safer, broader vaccine strategies.” He told the Washington Post that China in fact did develop a whole-virus vaccine against COVID-19, and he called it “pretty mediocre.” He also told us using an inactivated whole-virus platform for a vaccine “most likely ensures that we will not be able to make it in time for a new pandemic,” because it relies on the cultivation of large amounts of a virus in eggs or cells.
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