Authored by Maryanne Demasi via The Brownstone Institute,

For the first time in a generation, the US Centers for Disease Control and Prevention (CDC) has rewritten its official position on whether vaccines can cause autism.

This is a change that could reshape one of the most politically charged and emotionally fraught debates in modern medicine.

In a website update published on 19 November 2025, the agency now states that the long-standing claim “vaccines do not cause autism” is “not an evidence-based claim” because scientific studies “have not ruled out the possibility that infant vaccines cause autism.”

The page also acknowledges that “studies supporting a link have been ignored by health authorities.”

It’s difficult to overstate the significance of these statements. For nearly two decades, they would have been unthinkable for a federal public health agency.

The timing is equally striking.

The change arrives at a moment when the political and scientific landscape around vaccine safety is undergoing a marked shift inside the Trump–Kennedy administration.

For months, critics have accused Health Secretary Robert F. Kennedy Jr and several of the administration’s appointees of holding unconventional views on vaccine safety.

The CDC’s revised language now places the agency closer to Kennedy’s long-standing argument that federal agencies had ignored crucial evidence.

The CDC explains the shift by pointing to the Data Quality Act, which requires federal communications to accurately reflect the evidence.

Because studies have not excluded the possibility that infant vaccines could contribute to autism, the agency concedes that its long-standing categorical statement was not scientifically justified.

The update states plainly that scientific uncertainty remains, particularly for vaccines administered in the first year of life.

Scientific Uncertainty Finally Acknowledged

The information on the website draws a sharp distinction between the infant vaccine schedule — which includes DTaP, HepB, Hib, IPV, PCV and others — and the measles–mumps–rubella (MMR) vaccine.

For the MMR, the CDC continues to cite observational evidence showing “no association … with autism spectrum disorders,” describing the conclusion as supported by “high strength of evidence.”

But the agency also acknowledges that these studies had “serious methodological limitations” and were all retrospective epidemiological analyses, the type that cannot establish cause and effect or identify subgroups who may be more vulnerable.

The acknowledgement of limitations is unusually candid for a federal agency discussing vaccines and autism.

For the infant vaccine schedule, the shift is even more dramatic.

The CDC cites a series of authoritative reviews — including the 1991 and 2012 Institute of Medicine’s assessments, and the Agency for Healthcare Research and Quality’s review in 2021 — all concluding that the evidence was “inadequate to accept or reject” a causal relationship between early-life vaccines and autism.

In other words, the fundamental scientific question remains unresolved.

Political Dynamite

The political context makes this change even more consequential. Senator Bill Cassidy (R-LA), who chairs the Senate Health Committee, has been one of the most vocal critics of Kennedy’s vaccine views.

Cassidy has repeatedly insisted that the science on autism and vaccination was settled years ago. Now the CDC states that the claim “vaccines do not cause autism” does not meet evidence standards.

Remarkably, the CDC states that the headline phrase remains on the page only “due to an agreement with the chair of the U.S. Senate Health, Education, Labor, and Pensions Committee.”

The implication — that the wording is a political compromise rather than a scientific one — will undoubtedly invite scrutiny on Capitol Hill.

Attorney Aaron Siri, who has spent years litigating against federal agencies for greater transparency around vaccine safety, said the update marks a long-overdue shift in honesty from the CDC.

“It is an excellent step in the right direction for CDC to start telling the truth to the public about its past misdeeds and misrepresentations,” said Siri.

“Telling the truth and apologising for its prior misrepresentations is the only way the CDC will ever rebuild trust with the public,” he added.

How the Wakefield Saga Shaped Debate

For years, any attempt to revisit the vaccine–autism question was coloured by the fallout from the “Wakefield saga.”

The retracted 1998 Lancet paper became a shorthand for misinformation, and it allowed public health agencies to dismiss all subsequent concerns as if they were simply a continuation of that controversy.

The episode became a kind of cultural firewall.

Invoking Wakefield was an easy way to shut down inquiry, even when parents were describing patterns that had nothing to do with the MMR vaccine and everything to do with the expanding infant schedule.

The CDC’s admission that the evidence for early-life vaccines is “inadequate to accept or reject” a causal link — and that some studies “supporting a link have been ignored” — breaks the long-standing habit of waving away legitimate questions by pointing back to a decades-old scandal.

A Broad Recalibration

The CDC’s shift also aligns with a broader recalibration underway across federal health agencies in the US.

The Trump administration has ordered new NIH reviews of vaccine safety science, reinstated the Task Force on Safer Childhood Vaccines, and rejuvenated the CDC’s Advisory Committee on Immunization Practices (ACIP).

The pattern is unmistakable: agencies that once treated certain questions as “settled science” are now reopening them and its impact is likely to reverberate across the globe.

The CDC now admits the science has not ruled out potential links for vaccines given in infancy.

The website also notes that “about one in two surveyed parents of children with autism” believe vaccination played a role, often pointing to shots given in the first months of life or around the one-year mark.

Until now, those parents were often told their concerns were baseless. The agency’s new wording fundamentally alters that dynamic.

Changing the Conversation

In the US at least, public health agencies will no longer be able to respond to parental concerns with blanket denials.

Moreover, researchers studying plausible mechanisms — such as aluminium adjuvants, neuroinflammation, mitochondrial vulnerabilities, and immune activation — will find themselves in an environment that formally recognises these questions as scientifically legitimate.

Informed consent practices may need to be revisited as the existence of uncertainty is formally acknowledged.

And lawmakers who insisted that the science was settled will now face uncomfortable questions about why federal agencies relied on definitive messaging that did not meet evidence standards.

To be clear — the CDC’s update does NOT assert that vaccines cause autism. What it does say — with clarity the agency has avoided for years — is that the available evidence has not established that they do not, at least for the vaccines given in early infancy.

That distinction may seem subtle, but it represents a profound shift in how the conversation is framed and will undoubtedly impact the personal experiences of families raising autistic children.

For the first time that I can remember, the question of vaccines and autism is no longer treated as taboo. It has been recast — at the CDC’s own hand — as a research question that demands proper investigation.

The shift may prove to be one of the most consequential public health developments of the decade, and it suggests that something significant is moving behind the scenes in the federal agencies that once seemed immovable.

Old CDC Website:

Updated CDC Website:

Republished from the author’s Substack