On September 4, 2025, at a hearing before the Senate Finance Committee, Health and Human Services Secretary Robert F. Kennedy Jr. faced intense questions from many senators about his vaccine policy, including his stance on Covid-19 vaccines and mRNA vaccine technology.
Kennedy agreed that President Donald Trump’s signature initiative to produce Covid-19 vaccines in nine months was a tremendous achievement, but he also argued that the Covid-19 vaccine would cause widespread harm, including those in young people.
The questions specifically pointed out came from Republican Sen. Bill Cassidy of Louisiana. This comes after Kennedy was the doctor who provided the final vote needed to confirm Kennedy in February 2025, and promised that Kennedy would not change the Centers for Disease Control and Prevention processes to recommend the vaccine. Cassidy pointed out that the restrictions and confusion caused by the CDC’s new rules regarding Covid-19 vaccines “I think we’re effectively denying people’s vaccines.” Kennedy replied, “Well, you’re wrong.”
At the hearing, Kennedy endured the decision to cut HHS funding to US$500 million for 22 research contracts on mRNA vaccine technology. HHS says it will inject these funds into research into traditional approaches to designing vaccines that were first used more than 200 years ago. With such vaccines, called whole virus vaccines, the human immune system is presented throughout the virus, often weakened or inactivated. This switcher has confusing many scientists.
A few days before the hearing, on September 1, Trump requested that the drug company prove that the Covid-19 mRNA vaccine works, and the CDC said it was “torn apart by this question.” It was his first general approval of chaos that shook the CDC amid the firing of director Susan Monares and subsequent resignations of four high-level agency staff.
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Meanwhile, public health experts and HHS staff are calling for Kennedy to be fired, and several senators at the hearing repeated the call.
As a vaccine scholar who has researched and developed vaccines for over 35 years, we find that the science behind mRNA vaccine technology is widely falsely wrong. This misinformation shaping the US long-term health policy, making it urgent to correct records.
Is mRNA vaccines not safer than whole virus vaccines?
HHS defended the cancellation of mRNA vaccine studies based on an unpeer-reviewed compilation of selected publications called Covid-19 mRNA “vaccines.” The document lists around 750 articles that are allegedly explained the harm caused by the mRNA vaccine against Covid-19. However, most of these articles are not about the vaccine, but about the harm of infecting SARS-Cov-2, the virus that causes Covid-19. And what’s not particularly present is the vast amount of data showing that mRNA vaccines actually prevent these harms.
For example, the document used to justify RFK Jr.’s claims about mRNA vaccines highlights 375 studies reporting that only viral spike proteins may be produced when the virus is replicated. This is true. However, the document marshals this evidence in support of the claim that mRNA vaccines designed to produce spike proteins cause the same harm. This is not accurate.
Viral replication leads to the uncontrolled production of large quantities of proteins, but the methods produced by mRNA vaccines are very different. Vaccines produce small, controlled amounts of spike protein within several cells. This is sufficient to induce an immune response without causing damage. And by blocking virus replication, it reduces the amount of spike protein in circulation, actually having the opposite effect.
What about side effects like myocarditis?
Early reports flagged a type of cardiac swelling called myocarditis, a rare side effect of mRNA vaccines, especially for young men ages 18 to 25 years old after booster doses. A 2024 review identified roughly 20 of the 1 million people who received the vaccine. However, the same study found that people who have not been vaccinated are 11 times more likely to develop myocarditis after Covid-19 infection than those who have been vaccinated.
Additionally, another 2024 study showed that people who developed myocarditis after vaccination had fewer complications than those who developed the condition after being infected with Covid-19.
Do mRNA vaccines make them resistant to the SARS-COV-2 virus?
Another claim from the edits of mRNA vaccines cited as a reason to cut funding for mRNA technology is that mRNA vaccines cause mutations in the SARS-COV-2 virus, making them resistant or susceptible to vaccines.
When a virus replicates to a host, it produces millions of copies of the genetic material. Mutations are naturally occurring copying errors during the replication process. These acquired mutations produce new variants. So, both the Covid-19 mRNA and the entire virus vaccine are updated annually.
Slowing the replication of a virus slows the speed at which the virus can acquire new mutations. Both mRNA and whole virus vaccines help to reduce the appearance of resistant viruses, as both mRNA and whole virus vaccines stop or slow virus replication.
The virus can mutate to escape from antibodies, but mRNA vaccines do not cause the emergence of more virulent strains for at least two reasons. First, mRNA vaccines induce an immune response that can attack the virus at multiple spots, so many mutations must be come up at once to escape vaccine protection. Second, even if the virus can acquire all these mutations, they are likely to weaken it and cannot even cause or infect it.
mRNA vaccines and a new SARS-COV-2 variant
Kennedy announced a cutback in mRNA vaccine research on August 5, 2025, which claimed that mRNA vaccines do not work against respiratory viruses, and HHS is heading towards a “safeterial and broader vaccine platform that is effective even if the virus mutates.”
While both whole-viral and mRNA vaccines were protected against COVID-19 and prevented hospitalization and death of millions of people around the world between 2020 and 2024, there is clear evidence that mRNA-based vaccines provided significantly better protection than all-viral vaccines. Also, in the case of Covid-19, mRNA vaccines are more effective against new variants that appear than the entire virus vaccine as the virus mutates.
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The Covid-19 mRNA vaccine began with a very high effect of over 94%. When the SARS-Cov-2 delta and Omicron variants appeared in the spring and fall of 2021, mRNA vaccines became less effective in preventing infection. However, while they remained very effective in preventing severe illness, severe illness and hospitalization rates remained high in those who were not vaccinated.
This is because mRNA vaccines induce the immune system to create both antibodies called T cells and specialized immune cells. These elements recognize multiple elements of the virus, including those that do not change, allowing for significant protection against new variants.
Furthermore, there are superpowers in mRNA vaccines that are currently inconsistent with other types of vaccines. Can be updated and manufactured quickly within 2-3 months. To develop a vaccine for the entire virus, researchers must first spend several months of isolation and transmission of the virus. Conversely, to create an mRNA vaccine, you simply need to sequence the genetic code of the virus. This is a process that takes several hours today.
If a new pandemic begins today, mRNA vaccines are now the only type of vaccine that can be developed quickly enough to destroy its spread.
The future of mRNA vaccine technology
Thirty years ago, when scientists first began developing mRNA vaccine technology, they recognized the possibility of overcoming major limitations on all viral vaccines, namely slow production times, and limited ability to protect against new viral variants. Today, mRNA vaccines are being developed to prevent or treat diseases such as HIV and cancer, as well as autoimmune and genetic diseases.
Of course, this technology can be further improved. New mRNA vaccine technologies aim to make mRNA vaccines easier to store, faster short-term side effects, eliminate rare risks of myocarditis, and block respiratory infections more quickly.
The National Institutes of Health is raising funds away from new mRNA technologies for a single project to develop universal vaccines based on traditional viral vaccine technologies. Universal vaccines are urgently needed to provide broader protection against ever-changing respiratory viruses such as the flu, a major pandemic threat.
A 2022 study in mice and ferrets showed that the supporting universal influenza vaccine NIH is committed. However, multiple studies of potential universal influenza vaccines based on mRNA technology have shown to be even more potential. Such vaccines can induce a wider immunity than whole virus vaccines by inducing T-cell responses with antibodies targeting a wider range of influenza viruses.
It is difficult to square these benefits with the fact that HHS and NIH have named the new universal vaccine platform “Generation Gold Standard,” which is planned. This effort seems to be similar to eliminating all e-bike technology and telling everyone who wants one to reach a single brand of 10-speed bikes.
And if we abandon research on mRNA vaccines, it could lead to unnecessary losses, whether the potential drug is an unexplored drug or whether it is unprepared for the pandemic.
This article has been updated to include details of the September 4, 2025 Kennedy hearing.
This edited article will be republished from the conversation under a Creative Commons license. Please read the original article.
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