CDC Revises 'Autism and Vaccines' Webpage — Scientists and Advocates Sound Alarm

The Centers for Disease Control and Prevention quietly revised its “Autism and Vaccines” webpage, replacing a clear, long-standing declaration that "vaccines do not cause autism" with more ambiguous language suggesting studies have not entirely ruled out any possibility. The previous page opened with: "Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD)," followed by a bold statement: "Vaccines do not cause autism."

What changed

The updated page now begins: "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." The phrase "Vaccines do not cause autism" remains visible on the page but carries an asterisk directing readers to a note explaining it was retained following an agreement with the chair of the Senate Health, Education, Labor, and Pensions Committee, Sen. Bill Cassidy (R-La.). That senator reportedly cast a pivotal vote to advance a cabinet nominee after assurances the nominee would not undermine public confidence in vaccines.

Responses from officials and experts

Sen. Cassidy emphasized in a post on X that parents should hear vaccines for measles, polio, hepatitis B and other childhood diseases are "safe and effective and will not cause autism," calling any contrary statements "wrong, irresponsible, and actively" harmful to public health. An HHS spokesperson said the agency is updating the CDC site to reflect what it called "gold standard, evidence-based science."

"Can we trust what's coming from CDC anymore? I don't know the answer to that question," said Dr. Sean O'Leary, chair of the infectious disease committee at the American Academy of Pediatrics, calling the change a "tragic moment" for public health.

Autism advocates and scientists reacted strongly. The Autism Science Foundation said it was "appalled" that the page has been changed and described the revision as replacing prior science-based guidance with misinformation. Alison Singer, the foundation's co-founder, warned that repeatedly reopening disproven questions wastes resources that could be used to find the true causes of autism.

Colin Killick, executive director of the Autistic Self-Advocacy Network, noted that the link between vaccines and autism has been studied extensively with no credible evidence of causation, and said the revision risks endangering both autistic people and the broader public by undermining vaccine confidence.

Context and scientific perspective

The revised page also highlights a correlation between the rise in autism diagnoses and the increase in the number of childhood vaccines. Many researchers say that the growing number of diagnosed cases is better explained by an expanded diagnostic definition of ASD, improved screening and surveillance, and greater awareness — not by vaccination. Major reviews of the evidence have repeatedly found no causal connection between routine childhood vaccinations and autism.

The change has renewed debates over how public health agencies communicate uncertainty, how political pressure may affect science messaging, and how to maintain public trust in routine immunizations that prevent serious disease.