The Department of Health and Human Services has defended cuts to vaccine research with statements that mislead on the safety of mRNA technology, despite an extensive history of testing.
HHS recently terminated a $766 million award to Moderna for developing mRNA vaccines against influenza viruses that run a risk of causing a pandemic, in the midst of an ongoing H5N1 bird flu outbreak in poultry and livestock. Top administration officials have been silent on the reasoning, but HHS spokespeople criticized the mRNA platform.
“After a rigorous review, we concluded that continued investment in Moderna’s H5N1 mRNA vaccine was not scientifically or ethically justifiable,” HHS Communications Director Andrew Nixon said in a statement published by multiple news outlets. “This is not simply about efficacy—it’s about safety, integrity, and trust. The reality is that mRNA technology remains under-tested, and we are not going to spend taxpayer dollars repeating the mistakes of the last administration, which concealed legitimate safety concerns from the public.”
Responding to a request for comment on the ending of funding for projects on mRNA HIV vaccines, HHS Press Secretary Emily Hilliard gave a similar statement, repeating that the technology is “under-tested,” and again referring to safety concerns that the last administration “concealed.”
A more recent statement from Nixon on the cancellation of the bird flu vaccine funding, given to KFF Health News, cited “mounting evidence of adverse events associated with COVID-19 mRNA vaccines,” although the statement did not specify what evidence it was referencing.
The safety of approved mRNA vaccines is well-established and, as with other vaccines, continues to be monitored by multiple surveillance systems.
HHS did not respond to our request for more information on what safety concerns were “concealed,” but vaccine safety experts told us they were unaware of evidence that officials hid safety concerns about mRNA vaccines.
“By now, the mRNA vaccines are no longer ‘new’ or ‘experimental,’” Dr. William Schaffner, a professor of infectious diseases at the Vanderbilt University Medical Center, told us. Hundreds of millions of doses of the mRNA COVID-19 vaccines have been administered in the U.S., and the vaccines have also been distributed to people around the world. “We know as much about these vaccines as we know about the vaccines we give our babies here and around the world,” Schaffner said. “So these are now extremely well studied vaccines, and we know about their safety.”
The disinvestment in some mRNA-related projects comes amid a climate of anti-mRNA vaccine sentiment within the government. Lawmakers in some states have introduced legislation attempting to ban mRNA technology, and new requirements from the Food and Drug Administration will likely narrow the populations for whom the mRNA COVID-19 vaccines are approved.
National Institutes of Health Director Dr. Jay Bhattacharya told Politico last month that people “now think that mRNA is a bad platform,” blaming “government pressure” to get vaccinated and breakthrough COVID-19 cases among the vaccinated. This “widespread public skepticism,” he said, made the platform difficult to use.
HHS Secretary Robert F. Kennedy Jr. helped feed this mRNA vaccine skepticism by spreading false a misleading information on COVID-19 vaccines for years.
Dr. Jesse Goodman, a professor of medicine and infectious diseases at Georgetown University and chief scientist at the FDA between 2009 and 2014, told us that cutting research into mRNA vaccines is counterproductive if the goal is to gain more information on mRNA vaccine safety. He added that the mRNA platform is the only technology currently that “could allow an extremely rapid response” if an influenza pandemic were to occur, and he compared defunding it to “abandoning the lead horse in a race when it’s already shown it can win other races.”
“It just makes no sense to me,” he said.
About a month before ending the Moderna grant, HHS announced funding for an in-house NIH project to develop universal vaccines for coronaviruses and influenza viruses, including bird flu, using an old technology, drawing skepticism and puzzlement from many experts in the vaccine field.
Extensive Safety Testing for mRNA Vaccines
HHS’ claim that mRNA technology is “under-tested” flies in the face of the significant testing the COVID-19 mRNA vaccines have undergone.
The Pfizer/BioNTech and Moderna COVID-19 vaccines were the first mRNA vaccines to be approved by the FDA. The vaccines were developed in response to the coronavirus pandemic that has killed millions of people globally and would have killed millions more without a vaccine, studies have estimated. The mRNA, or messenger RNA, in the vaccines provides instructions for cells to make small quantities of spike protein from the coronavirus, preparing the immune system to recognize the actual virus in the future.
The “mRNA vaccine technology is not ‘under-tested’ in any meaningful scientific sense,” vaccinologist Helen Petousis-Harris of the University of Auckland told us in an email. “While it is a relatively new platform in human vaccines, it is now one of the most extensively studied due to the global rollout of COVID-19 vaccines.” (Petousis-Harris is also co-director of the Global Vaccine Data Network. The group’s funding from the U.S. Centers for Disease Control and Prevention for work on COVID-19 vaccine safety was recently canceled, according to the GVDN website and an HHS spreadsheet of terminated funding.)
Petousis-Harris explained that the mRNA vaccines for COVID-19 were studied in large-scale clinical trials including tens of thousands of participants before they were authorized for use and eventually approved.
Since the vaccines were rolled out beginning in late 2020, the U.S. government, other governments around the world and independent researchers have continued to perform studies and safety surveillance, Petousis-Harris said.
“There may be some serious adverse reactions that occur one in a million doses delivered, and obviously, if you think about it, we cannot expect that they would appear in a clinical trial for us to observe and to study,” Schaffner said.
In the U.S., surveillance systems include the Vaccine Adverse Event Reporting System, which compiles reports of health events that occur following vaccination, whether caused by the vaccine or not, in order to identify patterns that require further scrutiny. The government increased requirements for health care providers to report possible side effects during the COVID-19 vaccine rollout. Another system, the Vaccine Safety Datalink, uses records from health care organizations to help further investigate links between vaccination and any health problems.
With the COVID-19 vaccines, the CDC also launched a new system, called v-safe, to ask people about their health after vaccination. There are a number of other U.S. systems, including ones based on data from the Department of Defense, the Veterans Administration and Medicare.
“Because it was recognized that the mRNA technology was a new technology and that this vaccine it was anticipated would be recommended broadly to the population because obviously we were in a pandemic circumstance, the vaccine adverse event surveillance system was actually enhanced and made more elaborate once the COVID vaccines started to be used,” Schaffner said. “The mRNA vaccines are actually extraordinarily safe.”
Of course, as we have written previously, no vaccine or other medical product is 100% safe, and experts weigh risks and benefits before deciding whether to recommend vaccines for particular groups of people and at particular times.
“What we know about them is they saved millions of lives from COVID,” Goodman said of the COVID-19 vaccines. “We know they’re not perfect. They have rare significant side effects.” But he said this is a reason to try to improve the vaccines, not “discard them.”
During the vaccine rollout, safety surveillance — internationally and in the U.S. — picked up on a safety signal indicating a rare risk of myocarditis, a form of heart muscle inflammation, and pericarditis, or inflammation of the heart lining, from the two mRNA COVID-19 vaccines. The side effects occurred particularly in teenage and young adult males following the second vaccine dose, and the CDC continued to judge that benefits of vaccination outweighed risks. Myocarditis can also occur after COVID-19. Cases associated with the disease tend to be moresevere than vaccine-associated myocarditis.
Vaccine-associated myocarditis has been associated with “generally mild outcomes and full recovery,” Petousis-Harris said.
Myocarditis after COVID-19 vaccination has become even rarer over time and has not shown a significant link in the last three years, according to the most recent data presented to CDC’s Advisory Committee on Immunization Practices in April.
It’s worth noting that myocarditis is not unique to mRNA vaccines, as it’s also a rare side effect of Novavax’s protein-based COVID-19 vaccine.
Furthermore, safety research into mRNA vaccines did not start and end with the COVID-19 vaccines. As we wrote back in 2020, the mRNA platform had been studied prior to the pandemic, including in early-phase clinical trials for diseases other than COVID-19. And any new mRNA vaccine will undergo further testing for safety.
Unsubstantiated Claims of Concealment
As we’ve said, HHS only vaguely referred to safety concerns the Biden administration allegedly “concealed” and did not answer our message seeking clarification. However, a Senate subcommittee led by Sen. Ron Johnson, a Republican from Wisconsin, on May 21 held a hearing on the “corruption of science and federal health agencies,” which alleged that health officials “downplayed and hid” myocarditis.
Schaffner, Petousis-Harris and Goodman all told us evidence is lacking that the government concealed mRNA COVID-19 vaccine safety concerns.
Moreover, as we’ve said, there isn’t reason to believe mRNA vaccines are uniquely risky.
“There is no credible or substantiated evidence that the Biden administration concealed legitimate safety concerns about mRNA vaccines that I am aware of,” Petousis-Harris said.
Goodman said it is fair to look back at judgments made under challenging circumstances and question whether communication could have been improved or sped up. However, “I haven’t heard any convincing evidence that somebody tried to keep it secret,” he said of myocarditis, adding that “certainly information was out there that there was myocarditis in these young people.”
A report released in conjunction with the hearing shows deliberation among officials over how to communicate about myocarditis amid some uncertainty about whether the vaccines were causing the condition. The deliberation does not reveal plans for a cover-up or concealment.
Documents show that representatives from Israel’s Ministry of Health and the CDC exchanged emails on the topic of myocarditis in late February 2021. Reporting showed Israeli health authorities were looking into a possible connection between mRNA vaccination and myocarditis in April 2021, which U.S. and international news outlets covered at the time, and the CDC director told reporters that the agency was looking into reports of myocarditis but had not “seen a signal.”
The subcommittee report particularly highlighted a sequence of events in late May, in which officials drafted and then did not send a message via the CDC’s Health Alert Network. This type of bulletin is intended to communicate to public health workers about “urgent public health incidents,” according to the CDC website. The officials ultimately decided to further communicate about the possible risk by posting on the CDC website about new clinical considerations surrounding myocarditis and pericarditis after vaccination.
It is worth noting that during the period in which officials were discussing whether to issue this specific type of alert, it was not a secret that myocarditis remained a possible safety concern. Outlets including the New York Times, NBC News and Reuters were covering the potential risk of myocarditis, based on information on the topic the CDC was already putting out. A CDC working group confirmed a “likely association” in June 2021 during an ACIP meeting.
“Claims that the administration ‘concealed’ risks often refer to the timing or emphasis of risk communication, not to actual cover-ups,” Petousis-Harris said. “The known risks were not hidden—they were documented in scientific and regulatory disclosures.”
