NEW YORK – In a surprising move, the Centers for Disease Control and Prevention (CDC) has altered its website to challenge the longstanding scientific assertion that vaccines are not linked to autism. This shift has sparked significant backlash from both public health officials and experts in the field of autism.

On Wednesday, the CDC updated its “vaccine safety” page, introducing a statement that reads, “The assertion that vaccines do not cause autism lacks an evidence-based foundation.”

This adjustment is part of a broader effort by the U.S. Department of Health and Human Services to reevaluate—and cast doubt upon—established scientific agreements concerning the safety of vaccines and similar medical products.

The revision has drawn immediate criticism from scientists and advocates dedicated to uncovering the roots of autism.

“We are deeply concerned and disappointed that the CDC’s ‘Autism and Vaccines’ webpage has been modified to include anti-vaccine language and falsehoods about the relationship between vaccines and autism,” the Autism Science Foundation expressed in a statement released Thursday.

Widespread scientific consensus and decades of studies have firmly concluded there is no link between vaccines and autism. “The conclusion is clear and unambiguous,” said Dr. Susan Kressly, president of the American Academy of Pediatrics, in a statement Thursday.

“We call on the CDC to stop wasting government resources to amplify false claims that sow doubt in one of the best tools we have to keep children healthy and thriving: routine immunizations,” she said.

The CDC has, until now, echoed the absence of a link in promoting Food and Drug Administration-licensed vaccines.

But anti-vaccines activists — including Robert F. Kennedy Jr., who this year became secretary of Health and Human Services — have long claimed there is one.

It’s unclear if anyone at CDC was actually involved in the change, or whether it was done by Kennedy’s HHS, which oversees the CDC.

Many at CDC were surprised.

“I spoke with several scientists at CDC yesterday and none were aware of this change in content,” said Dr. Debra Houry, who was part of a group of CDC top officials who resigned from the agency in August. “When scientists are cut out of scientific reviews, then inaccurate and ideologic information results.”

The updated page does not cite any new research. It instead argues that past studies supporting a link have been ignored by health authorities.

“HHS has launched a comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links. Additionally, we are updating the CDC’s website to reflect gold standard, evidence-based science,” said HHS spokesman Andrew Nixon, in an email Thursday.

A number of former CDC officials have said that what CDC posts about certain subjects — including vaccine safety — can no longer be trusted.

Dr. Daniel Jernigan, who also resigned from the agency in August, told reporters Wednesday that Kennedy seems to be “going from evidence-based decision making to decision-based evidence making.”

U.S. Sen. Bill Cassidy, a Louisiana Republican, earlier this year played a decisive role in approving Kennedy’s nomination for HHS secretary. Cassidy initially voiced misgivings about Kennedy, but in February said Kennedy had pledged — among other things — not to remove language from the CDC website pointing out that vaccines do not cause autism.

The new site continues to have a headline that says “Vaccines do not cause autism,” but HHS officials put an asterisk next to it. A note at the bottom of the page says the phrasing “has not been removed due to an agreement with the chair of the U.S. Senate Health, Education, Labor, and Pensions Committee that it would remain on the CDC website.”

Cassidy’s spokespersons did not immediately respond to a request for comment.

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