CDC Again Changes Wording About Vaccines and Autism

Before Nov. 19, 2025, the U.S. Centers for Disease Control and Prevention’s (CDC) featured language on its website declaring point blank that vaccines do not cause autism. Specifically, at that time the CDC stated: “Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD). No links have been found between any vaccine ingredients and ASD.”^{1 2 3 4} 

On Nov. 19, 2025 the text about vaccines and autism was changed CDC officials to inform the reader that the possibility that vaccines could contribute to the development of autism had not been ruled out. The health agency’s website language changed to:

“Vaccines do not cause autism” is not an evidence-based claim. Scientific studies have not ruled out the possibility that infant vaccines contribute to the development of autism. However, this statement has historically been disseminated by the CDC and other federal health agencies within HHS to prevent vaccine hesitancy.⁵

Pro-Mandatory Vaccination Proponents Oppose 2025 Change to Language on Vaccines and Autism

Additionally, the language on the CDC’s website in 2025 stated that the U.S. Department of Health and Human Services (DHHS) had “launched a comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links.” That was perfectly reasonable and urgently needed language given the unrelenting, ever expanding autism epidemic.⁵

Predictably, however, it managed to rile a lot of people in Congress and within the pharmaceutical, medical, and public health industries because it publicly revisited the question of whether vaccines can cause autism. It is a decades-old debate that many vaccine apologists say should be over because they say “the science has been settled” and vaccines do not cause autism, and any suggestion that the vaccine-autism association should be investigated will only fuel more “vaccine hesitancy.”

According to Alison Singer, co-founder and president of the Autism Science Foundation (ASF), while researchers “can’t do a scientific study to show that something does not cause something else,” there are a “mountain of studies that we have exonerating vaccines as a cause of autism.”¹ She added:

I think the question of whether vaccines cause autism is one that science can answer, and science has answered it.¹

Fiona Havers, MD, a former medical epidemiologist with the CDC, characterized the November 2025 language change on the CDC’s website as little more than “anti-vaccine propaganda” that “contradict[s] decades of scientific research.”³ Pediatrician Susan Kressly, MD, president of the American Academy of Pediatrics (AAP), stressed:

There’s no link between vaccines and autism. Anyone repeating this harmful myth is misinformed or intentionally trying to mislead parents.  that anyone repeating the “harmful myth” is misinformed or intentionally trying to mislead parents. We call on the CDC to stop wasting government resources to amplify false claims that sow doubt…³

The Infectious Disease Society of America stated:

There is no scientific rationale for CDC to change its long-standing assertion that there is no link between vaccines and autism. This change is not driven by science but by politics and will only serve to increase mistrust in science and medicine.²

“This change to CDC language undermines the agency’s scientific integrity, damaging its credibility on vaccines and other health recommendations,” said former CDC director Mandy Cohen, MD, MPH. “Most concerning, it risks endangering children by driving down vaccination rates and leaving kids vulnerable to preventable diseases like measles and whooping cough.” Sean O’Leary, MD, MPH, chair of the AAP’s Committee on Infectious Diseases, said he worried that the changes to the website would “scare parents and further stigmatize” people with autism.¹

Senator Cassidy Objects to CDC Website Lanuage on Vaccines and Autism

Perhaps the person most riled with the changes to the CDC’s website made in November 2025 has been U.S. Senator Bill Cassidy of Louisiana, chair of the Senate Health, Education, Labor, and Pensions (HELP) Committee. In a post on X, Sen. Cassidy wrote, “Redirecting attention to factors we definitely know DO NOT cause autism denies families the answers they deserve.” He sought to reassure the public that vaccines are “safe and effective and will not cause autism” and that “any statement to the contrary is wrong, irresponsible, and actively makes Americans sicker.”^{1 2 3}

It is widely known that Secretary of Health and Human Services Robert F. Kennedy, Jr. played a role in having the agency’s vaccine/autism language revised in 2025.  Cassidy said that Kennedy in his HELP confirmation hearings in January 2025 had assured him that the “CDC will not remove statements on their website pointing out that vaccines do not cause autism.” Kennedy kept his word, but did alter the statement by truthfully adding “Vaccines do not cause autism is not an evidence-based claim” to the CDC’s website page.^{2 6 7 8}

CDC Language on Vaccines and Autism Again Amended

Now, it looks like Cassidy is determined to turn the clock back. Reportedly, in exchange for his support to confirm President Trump’s nominee to be the next director of the CDC, Erica Schwartz, MD, JD, MPH, Cassidy has made a deal with Kennedy on the CDC’s language. A recent CNN article quoted Cassidy as saying… “As a sign of good faith, [Health and Human Services] modified the CDC’s autism and vaccines webpage.”^{8 9}

The latest language about vaccines and autism posted July 23, 2025 on the CDC website now reads:

Scientists have not identified the root causes of autism. HHS continues to support rigorous scientific research and will update this page as reliable new evidence becomes available.^{5 8}

Commenting on the new website language, Cassidy said this was at least “a start.” It’s clear that he expects more from Kennedy on this issue, and certainly more from Dr. Schwartz if she is confirmed for the top CDC post.

What Cassidy shouldn’t expect is a return to the ol’ “Vaccines do not cause autism” sloganeering. That ship has sailed.

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