The main campus of the Center for Disease Control and Prevention (CDC) in Atlanta, Georgia, U.S., August 27, 2025. REUTERS/Alyssa Pointer

(Reuters) -The U.S. Centers for Disease Control and Prevention updated its website on Wednesday to say that claims about vaccines not causing autism are not "evidence-based."

Vaccine skeptic and U.S. Health and Human Services Secretary Robert F. Kennedy Jr. as well as U.S. President Donald Trump have promoted the theory - contrary to scientific evidence - that childhood vaccines are a cause of autism. But the CDC's website previously said "studies have shown there is no link between receiving vaccines and developing autism spectrum disorder."

As of Wednesday night the agency's website states: "The claim 'vaccines do not cause autism' is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism." It added that health authorities have "ignored" studies supporting the link between the two.

The agency kept the header "Vaccines do not cause autism" on its web page, saying that it has not been removed due to an agreement with Senator Bill Cassidy, chairman of the U.S. Senate's Committee on Health, Education, Labor and Pensions.

The anti-vaccine group Children's Health Defense, which was previously led by Kennedy, applauded the changes to the CDC's website.

"The CDC is beginning to acknowledge the truth about this condition that affects millions, disavowing the bold, long-running lie that 'vaccines do not cause autism,'" the group said on X.

Kennedy has linked vaccines to autism and sought to rewrite the country's immunization policies.

Trump has also linked autism to the taking of pain medication Tylenol by pregnant women, a claim that is also not backed by scientific evidence.

Autism is a neurological and developmental condition marked by disruptions in brain-signaling that cause people to behave, communicate, interact and learn in atypical ways.

The causes of autism are unclear, but no rigorous studies have found links between autism and vaccines, medications or components like thimerosal or formaldehyde.

(Reporting by Rishabh Jaiswal in Bengaluru and Michael Erman in New Jersey; Editing by Thomas Derpinghaus)