Robert F. Kennedy’s ongoing war against vaccines is escalating. Under his authority, the government has just stripped away its funding toward developing several next-generation vaccines reliant on messenger RNA technology.

The U.S. Department of Health and Human Services announced Monday that it is ending its development of mRNA vaccines organized through the Biomedical Advanced Research and Development Authority (BARDA). The revoked funding will affect nearly two dozen projects worth almost $500 million, including vaccine candidates intended to protect against bioterror threats like Ebola. As justification, health secretary RFK Jr. provided misleading arguments about the effectiveness of mRNA vaccines.

“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,” he said in the HHS announcement.

mRNA is a key component of our cells’ machinery. It’s used to encode and provide the instructions to cells on how to produce various proteins. mRNA vaccines work by instructing our cells to make specific proteins that trigger an immune response against their targets. In the case of the covid-19 mRNA vaccines—the first approved use of this technology—the vaccines tell cells to make a small, harmless bit of the coronavirus, the spike protein. These proteins then provoke a response from immune cells, allowing us to recognize the virus in the future without being exposed to the full infection.

The covid-19 mRNA vaccines are one of the greatest medical success stories of modern times. They were and remain highly effective at preventing severe illness and death from covid-19. And while no vaccine or drug is 100% risk-free, they have maintained an excellent safety record, especially compared to other covid-19 vaccines. Estimates vary depending on the study, but the vaccines undoubtedly prevented millions of deaths during the pandemic. mRNA vaccines are also faster to create than older vaccine types, and the covid-19 shots were indeed developed and cleared for use in record time.

RFK Jr.’s argument has a grain of truth, as is often the case with antivaccination talking points. The covid-19 mRNA vaccines don’t provide full protection against infection itself, and this protection wanes over time. The defense it provides against infection isn’t zero, however. Furthermore, the vaccines still protect against severe illness from covid-19 and can also shorten the duration of illness in those who do get infected.

Importantly, mRNA vaccines are also not particularly poor at protecting against upper respiratory infections. That’s partly why we need a yearly flu shot in the first place. Today’s approved flu vaccines, none of which are mRNA, can reliably prevent severe illness but are usually only modestly effective at preventing infection entirely. Other non-mRNA covid-19 vaccines aren’t substantially better at preventing infection either. These infections are generally harder to fully protect against with vaccines compared to diseases like measles, partly because viruses such as flu and covid-19 mutate quickly.

While mRNA vaccines aren’t worse than other vaccines and can have their advantages, their novelty has inspired antivaccination advocates to come up with all sorts of unique and false claims about their lack of safety. These claims range from calling the covid-19 mRNA shots gene therapy (they’re not) to falsely blaming them for making people magnetic.

Notably, RFK Jr. further justified the HHS’s cutting of mRNA vaccine funding by touting other vaccine technologies. “Let me be absolutely clear: HHS supports safe, effective vaccines for every American who wants them. That’s why we’re moving beyond the limitations of mRNA and investing in better solutions,” he said.

Kennedy’s actions speak louder than his words, however. For 20 years, he’s repeatedly misled the public about many different vaccines created long before the covid-19 mRNA shots, including the combination measles, mumps, and rubella (MMR) vaccine and the HPV vaccine. And during his tenure as HHS chief, he’s continued to support long-debunked vaccine-related myths.

In other words, there’s little reason to believe that RFK’s antivaccination crusade will stop at mRNA vaccines. But given how hugely important this technology has already been to humanity, the harm he causes to its further development could have far-reaching consequences. Scientists are not only working to develop mRNA vaccines for other germs but also to tackle conditions like cancer.