By Liz Essley Whyte and Sabrina Siddiqui

A Centers for Disease Control and Prevention webpage that previously made the case that vaccines don't cause autism now says they may.

The contents of the webpage came up during Health Secretary Robert F. Kennedy Jr. Senate confirmation process. Sen. Bill Cassidy (R., La.) in February said that if confirmed Kennedy had assured him that the "CDC will not remove statements on their website pointing out that vaccines do not cause autism."

The revised webpage says: "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. Studies supporting a link have been ignored by health authorities."

The new text posted Wednesday also notes that the Department of Health and Human Services has launched "a comprehensive assessment" to probe the causes of autism.

The webpage had been a focal point for both vaccine skeptics, who criticized its earlier language, and public health advocates, who wondered how far Kennedy would go to change federal agencies' language around vaccines.

The page previously said: "Studies have shown that there is no link between receiving vaccines and developing autism," citing a 2012 National Academy of Medicine review of scientific papers and a 2013 CDC study.

The new webpage says the CDC's previous assurances on vaccines and autism violated the Data Quality Act. It suggests aluminum adjuvants could be behind the rise in autism cases. "Though the cause of autism is likely to be multi-factorial, the scientific foundation to rule out one potential contributor entirely has not been established," the new page reads.

Kennedy in September suggested pregnant women taking Tylenol could also have fueled the increase in autism. He previously said pesticides, mold or environmental toxins could also be to blame.

Cassidy declined to comment.

He and Kennedy have increasingly sparred in recent months, as Cassidy has accused the health secretary of backpedaling on his vow to protect vaccine access. At a contentious Senate hearing in September, Cassidy criticized Kennedy for unwinding mRNA vaccine programs, replacing a key CDC advisory panel with vaccine skeptics, limiting access to Covid-19 vaccines, and firing former CDC Director Susan Monarez when she disagreed with his approach to vaccines.

Scientists have said that while it is impossible to prove "never" conclusively, no association has been proven between vaccines and autism. More than 25 peer-reviewed scientific articles have shown no link between autism and the MMR vaccine -- a longtime focus of vaccine skeptics due to a 1998 study suggesting there was a link, which was later retracted. A Danish study of more than 1.2 million children published earlier this year found no link between aluminum in vaccines and neurodevelopmental harm, including autism.

"It is absolutely definitive. There is no link between autism and vaccines. Zero. None," said Dr. Yvonne Maldonado, a professor of pediatrics, epidemiology and population health at Stanford Medicine.

The bottom of the CDC webpage now says that the header "Vaccines do not cause autism" remains on the site with an asterisk because of "an agreement" with Cassidy.

"We are updating the CDC's website to reflect gold standard, evidence-based science," HHS spokesman Andrew Nixon said.

Write to Liz Essley Whyte at liz.whyte@wsj.com and Sabrina Siddiqui at sabrina.siddiqui@wsj.com

(END) Dow Jones Newswires

November 19, 2025 23:49 ET (04:49 GMT)

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