One vaccine expert called the move, which cancels some $500 million in messenger RNA research contracts, a “giant step backward for science.”

US Health and Human Services is “winding down” its mRNA vaccine development and will instead fund other vaccine platforms through the Biomedical Advanced Research and Development Authority, the agency said Tuesday.

In an HHS video released yesterday on Fox News, Kennedy said that after consulting with experts from the National Institutes of Health (NIH) and the Food and Drug Administration (FDA), he decided to block further mRNA vaccine development because they "don't perform well against viruses that infect the upper respiratory tract."