RFK Jr. Says He Directed CDC to Revise Vaccine–Autism Guidance, Triggering Sharp Scientific Pushback

Health Secretary Robert F. Kennedy Jr. said in an interview that he personally ordered the U.S. Centers for Disease Control and Prevention to revise its vaccine-safety webpage to question the agency's long-standing assertion that vaccines do not cause autism.

The updated page replaces an unambiguous statement — "vaccines do not cause autism" — with language saying that the claim cannot be proven conclusively and noting studies some officials say have been overlooked. The revision surprised many current and former CDC staffers because it departs from the scientific consensus built on decades of research.

Experts push back

Public-health researchers and advocacy groups strongly disputed the website change, arguing it misleads the public by exploiting the philosophical problem of proving a universal negative. They point to extensive, rigorous research over many years that has found no causal link between vaccines and autism.

"No environmental factor has been better studied as a potential cause of autism than vaccines," the Autism Science Foundation wrote in a statement. "This includes vaccine ingredients as well as the body’s response to vaccines. All this research has determined that there is no link between autism and vaccines."

Kennedy acknowledged studies showing no association between autism and the mercury-based preservative thimerosal or the measles, mumps and rubella (MMR) vaccine, but he said gaps remain in vaccine-safety science and called for more research.

Political and administrative fallout

The website change intensified a rift between Kennedy and Sen. Bill Cassidy, chair of the Senate Health Committee. Cassidy said parents need to hear clearly that routine childhood vaccines "are safe and effective and will not cause autism," and called any statement to the contrary "wrong, irresponsible, and actively makes Americans sicker." The original wording remains on the page with a disclaimer noting it was retained after their agreement.

The revision is part of a broader pattern of moves by Kennedy that have unsettled many in the medical community: he has rescinded $500 million earmarked for vaccine development, replaced every member of a federal vaccine advisory committee, pledged to overhaul the federal vaccine injury compensation program, and dismissed former CDC leadership amid policy disagreements.

Dr. Sean O'Leary, chair of the infectious diseases committee at the American Academy of Pediatrics, called the website update "madness," warning that it undermines trust in public-health guidance. Officials at the Department of Health and Human Services did not immediately respond to requests for comment.

The dispute highlights ongoing tensions between a health secretary who questions aspects of vaccine policy and a scientific community that emphasizes the weight of existing evidence confirming vaccine safety with respect to autism.