Lynn R. Webster, M.D.

This article, in a slightly edited form, first appeared on American Council on Science and Health on December 4, 2025.

This essay examines how recent political intervention has reshaped the CDC’s public messaging on vaccines and autism. In Part 1, I explain why the scientific evidence on this topic has not changed—and why the CDC’s newly revised webpage represents a step backward for public health communication. Part 2 will explore how growing political influence has eroded trust in the agency over time.

PART 1

CDC’s Dangerous Hedge on Vaccines and Autism

What did the CDC just do to its autism page, and why is that scientifically wrong and harmful?

Not long ago, if a parent asked whether vaccines cause autism, I could answer simply and honestly: No. I could point them to a Centers for Disease Control and Prevention (CDC) fact sheet that opened with a blunt, reassuring sentence: “The evidence is clear: vaccines do not cause autism spectrum disorder (ASD).”

On November 19, 2025, that clarity vanished.

Without fanfare, the CDC rewrote its “Autism and Vaccines” webpage. The new version now says that the statement “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 asserts that studies suggesting a link have been “ignored by health authorities” and invokes the Data Quality Act* as justification for walking back the previous position.

The header “Vaccines do not cause autism” still sits at the top of the page, but it now carries an asterisk. Reporting indicates that the header was preserved only because of a political compromise with Senator Bill Cassidy during the confirmation of Health and Human Services (HHS) Secretary Robert F. Kennedy, Jr. Since then, Kennedy has confirmed that he personally ordered CDC to change the language, because he believes the agency’s previous statement “is not evidence-based.”

As a physician, I am used to scientific uncertainty. That is not what this is.

The science hasn’t moved. The CDC has.

For years, CDC’s own publications said essentially the same thing: Large, well-conducted studies show no link between childhood vaccines and autism. A widely cited CDC-sponsored summary of vaccine–autism research opened by stating that the evidence clearly shows vaccines do not cause ASD. A CDC autism FAQ updated as recently as 2024 similarly stated that studies “continue to show that vaccines are not associated with ASD.”

Those statements still match the broader scientific consensus. The American Medical Association responded to the new CDC page by reiterating that “an abundance of evidence from decades of scientific studies shows no link between vaccines and autism.” The Autism Science Foundation called the new page “distorted” and filled with “anti-vaccine rhetoric and outright lies,” noting that the previous science-based content has been replaced with messaging that “actually contradicts the best available science.”

Leading autism and disability organizations issued a joint statement expressing ‘deep disappointment” in CDC’s decision. The Infectious Diseases Society of America likewise warned that vaccine misinformation is already fueling measles outbreaks and urged a return to recommendations rooted in sound science.

None of these organizations are fringe. They represent the mainstream of medicine and public health expertise. They all say the same thing: Decades of rigorous studies involving millions of children in multiple countries have found no causal link between vaccines and autism.

Yet the CDC now insists that, because no study can absolutely prove a negative, the statement “vaccines do not cause autism” is not an “evidence-based claim.”

This is not how science works. If we demanded absolute, mathematically airtight proof of every negative claim, we would be unable to say that cigarettes don’t cure cancer, seat belts don’t cause leukemia, or sunscreen doesn’t cause diabetes. Science rarely closes every hypothetical loophole; it weighs the totality of the evidence and asks which conclusion is most consistent with reality.

Here, that conclusion is straightforward. Based on the accumulated data, vaccines do not cause autism. Saying otherwise is not humility. It is irresponsible.

Manufactured doubt in a fragile space

The revised webpage does more than hedge. It elevates speculative, low-quality studies and insinuates that “health authorities” have ignored them—without explaining that the reason is not conspiracy, but methodological weakness and failure to replicate. In doing so, CDC borrows from the playbook of tobacco companies and climate deniers. It takes a settled question, highlights a handful of outlier claims, and reframes consensus as arrogance.

That might seem like a technical quibble about phrasing on a government website. It isn’t. This is a topic already saturated with misinformation, grifters, and social-media echo chambers. The new language functions as a permission slip for discredited ideas, stamped with the CDC logo.

Who pays the price?

The immediate victims of the new autism page are families and clinicians.

For families with autistic children, the suggestion that “we can’t rule out vaccines” revives a painful narrative—that someone did this to their child by giving them a shot. Many parents spent years drowning in self-blame because of false claims about vaccines and autism before finally learning that the science did not support those fears. Autism advocates have long argued that framing autism primarily as an injury inflicted by vaccines stigmatizes autistic people and diverts attention away from where help is actually needed: support, accommodation, and inclusion. The new CDC language hands fresh ammunition to anti-vaccine activists who profit, politically and financially, from sowing fear and suspicion.

For clinicians, the CDC has created a contradictory mess. The headline declares that vaccines do not cause autism. The key points then insist that this claim is “not evidence-based,” accuse health authorities of ignoring supportive studies, and imply that decades of research showing otherwise are inconclusive. It is hard to imagine a more confusing message to give the public—or a more effective way to undermine confidence in all vaccine recommendations, not just those for children.

More broadly, each time the CDC allows its scientific messaging to be shaped by political demands, it reinforces a corrosive belief I hear increasingly from patients: that our public-health agencies cannot be trusted to tell the truth. That belief is dangerous even when it is understandable.

What honest messaging should look like

Honest messaging would look very different from the current page. It would acknowledge that vaccines, like all medical interventions, have risks—and then describe those real risks clearly and proportionately. It would state, without qualification, that autism is not among them. It would emphasize that people with autism deserve respect and support, not to be used as props in a culture war over vaccines.

That is the conversation I still try to have with families who have someone who has autism. I explain that we have looked for a link between vaccines and autism in many ways and many populations, and we have not found one. I remind them that refusing vaccines does not protect their children from autism—but it does leave them vulnerable to measles, whooping cough, and other preventable diseases now resurging as misinformation spreads.

The CDC’s new autism–vaccine page abandons that clarity. It does not reflect new data but, rather, a new political balance of power. It is, in that sense, a symptom of a deeper illness at the agency—one I will address in part 2 of this short series. For now, one thing remains as true as it was before November 19:

Based on decades of rigorous research, vaccines do not cause autism. Saying so plainly is not “anti-science.” Pretending we do not know the answer, to satisfy a political appointee, is.

Until CDC corrects the record, clinicians and independent scientific bodies will have to keep doing what the agency once did so well: Tell the public what the evidence actually shows, without flinching.

* Footnote: The “Data Quality Act” (also known as the Information Quality Act) is a two-sentence provision Congress tucked into Section 515 of the 2001 appropriations bill for Treasury and related agencies (Pub. L. 106-554). It directs the Office of Management and Budget to issue government-wide guidelines to ensure the “quality, objectivity, utility, and integrity” of information released by federal agencies, and to create a process for outside parties to challenge and seek correction of that information.

Lynn R. Webster, MD, is a pain and addiction medicine specialist and serves as Executive Vice President of Scientific Affairs at Dr. Vince Clinical Research, where he consults with pharmaceutical companies. He is also a Senior Fellow, Center for U.S. Policy

Dr. Webster is the author of the forthcoming book, Deconstructing Toxic Narratives—Data, Disparities, and a New Path Forward in the Opioid Crisis, to be published by Springer Nature. He is not a member of any political or religious organization