CDC revision on autism and vaccines triggers concern over evidence and public trust

A major update to the CDC’s webpage on autism and vaccines has triggered mostly confusion inside and outside of the agency among public health experts, many who say the new language requires clarification.

On Wednesday, November 19, the CDC revised its long-standing statement that vaccines do not cause autism—an update that has long stirred national debate. However, their update reads spotty that it could mean otherwise.

The revision, made to the CDC’s “Autism and Vaccines” page, now says that the claim “vaccines do not cause autism” is not evidence-based. According to the new text, studies have not ruled out the possibility that infant vaccines may contribute to autism, and research that supports a potential link has been ignored by health authorities.

The Wall Street Journal reported that the change appeared without review from some of the agency leaders responsible for vaccine and birth-defect research, leaving many employees blindsided.

According to Autism Speaks, there are many causes of autism. Research suggests that autism spectrum disorder develops from a combination of genetic influences and environmental influences, including social determinants of health. The organization noted that these factors can increase the risk of autism and shape how the condition presents in a child.

However, risk is not the same as cause. Autism Speaks emphasized that some gene changes linked with autism are also found in people without the disorder, and that most people exposed to environmental risk factors will never develop autism.

The Children’s Health Defense CEO, Marry Holland, Esq., said in an interview shared on X that this was great news to hear as advocates of vaccines being the cause of autism. Holland mentioned that advocates of this link “have been gaslit, and ridiculed, and mocked and marginalized for decades and this is a tremendous acknowledgement of the truth.”

She added that her team believes vaccines are the primary cause of autism, but that remains to be proven. She also said evidence exists that shows vaccines are the leading probable cause.
“This is the CDC finally telling the truth,” she said, adding that is just the beginning.

This shift follows a year of heightened focus on the topic caused by Health Secretary Robert F. Kennedy Jr., who has long questioned the safety of childhood vaccines. Earlier this year, Sen. Bill Cassidy, a Republican of Louisiana, said Kennedy had promised that the CDC would not remove language asserting that vaccines do not cause autism. Though the language hasn’t been removed completely, Wednesday’s revision leaves many with questions.

According to The Wall Street Journal, the CDC webpage previously stated that “studies have shown that there is no link between receiving vaccines and developing autism,” citing a 2012 National Academy of Medicine review and a 2013 CDC study.

HHS has now launched “a comprehensive assessment” of autism’s causes, including possible biologic mechanisms and potential causal links, the CDC said. The agency noted that these investigations will include examining aluminum adjuvants, mitochondrial disorders and neuroinflammation.

For many experts, the update raises urgent concerns, not only about the scientific basis of the claims but also about the effect the language might have on vaccine confidence.

The American Academy of Family Physicians (AAFP) issued a statement, stressing that “Vaccines do not cause autism. Decades of rigorous research have failed to provide credible scientific evidence linking vaccines to autism.”

The AAFP also cautioned that revisiting a disproven link could distract from research that may actually benefit those who are autistic and their families.

The AAFP further rejected related claims about acetaminophen (Tylenol) use during pregnancy, saying there is “no credible body of evidence” linking the medication to autism and calling the suggestion “unfounded.”

Cassidy, a physician, also pushed back publicly. Today, he wrote on X, “What parents need to hear right now is vaccines for measles, polio, hepatitis B and other childhood diseases are safe and effective and will not cause autism. Any statement to the contrary is wrong, irresponsible, and actively makes Americans sicker.”

He cited recent increases in measles and whooping cough cases, including two childhood measles deaths nationwide this year, as examples of the real dangers of vaccine hesitancy.

The political tensions surrounding the issue have been building for months. During Kennedy’s earlier confirmation hearings in January, Sen. Bernie Sanders pressed him directly on whether he acknowledged the scientific fact that vaccines do not cause autism. Sanders stressed that extensive research backs this conclusion, telling Kennedy, “The evidence is there. That’s it.” Kennedy responded by saying that if there were data proving this data to be true, he would feel the same.

The confusion deepened after a September press conference in which President Donald Trump, Health Secretary Kennedy, and other officials announced that the FDA would begin adding warnings to acetaminophen labels related to pregnancy. At the event, Kennedy suggested acetaminophen could contribute to rising autism rates—a claim many physicians quickly disagreed with.

Previously reported by Managed Healthcare Executive, researchers and autism specialists have taken LinkedIn and other platforms to reiterate that acetaminophen remains safe for pregnant women when used as directed and that autism does not have one single cause.

The revised CDC webpage leaves many unanswered questions.

While the agency said it’s now conducting a comprehensive assessment of autism’s causes, it does not explain why it overturned a clear, widely studied position without notifying internal experts. It also does not specify which studies supposedly “ignored by health authorities” support a vaccine-autism link or how those studies compare to research showing no connection.

For families affected by autism and for the medical community, the stakes are high, according to the AAFP. Autism prevalence has risen in recent decades, the agency added, and researchers continue to investigate genetic, environmental and developmental factors.

Experts at the AAFP warn that reopening this debate risks undermining trust in vaccines at a moment when preventable disease outbreaks are resurging.

As the HHS review moves forward, physicians and other health professionals said they will continue demanding transparency and rigorous evaluation.

“The assertions made by HHS must be met with the full force of scientific scrutiny,” the AAFP said. “We owe that to the public, to science and most of all, to the families who trust us to protect their health.”

The American Medical Association also echoed similar beliefs by sharing in a statement that the association is “deeply concerned that perpetuating misleading claims on vaccines will lead to further confusion, distrust, and ultimately, dangerous consequences for individuals and public health.”

A joint statement from the Infectious Disease Society of America released today said that “Vaccine misinformation has dangerous effects. Right now, the ongoing measles outbreak in the United States is putting the country on the verge of losing its long-held status as having eliminated measles. We need to quickly return to medical information and recommendations being based on sound science, not unverified opinions.”