CDC Revises Vaccine and Autism Messaging

A webpage from the Centers for Disease Control and Prevention (CDC) that previously stated, without ambiguity, that vaccines do not cause autism has undergone a revision. The new wording hints—without providing evidence—that health officials may have overlooked potential links between vaccinations and autism.

The updated text reads, “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.” This change was made public on Wednesday and first reported by a major news outlet.

Pediatricians and vaccine specialists have consistently argued that autism is one of the most examined childhood disorders, and credible research has consistently failed to demonstrate any association with vaccines.

This new messaging marks a significant departure from decades of established research indicating that any correlation between vaccines and autism has been rigorously analyzed and debunked.

Many scientists and autism researchers were taken aback by the change in tone.

“This is madness,” stated Dr. Sean O’Leary, chair of the American Academy of Pediatrics’ infectious disease committee, during a press briefing. He emphasized that extensive investigations into environmental factors contributing to autism have repeatedly shown that vaccines are not included among those factors. “They do not cause autism. Period.”

The Autism Science Foundation expressed its shock at the revision, labeling the revised CDC messaging as “anti-vaccine rhetoric and outright lies” about the relationship between vaccines and autism.

“Proposing that vaccines cause autism is not only scientifically inaccurate,” said ASF director Alison Singer at the briefing, “it also deeply stigmatizes autistic individuals and their families. It implies that autism results from parental choices, as if it’s a preventable condition.”

Importantly, the updated webpage also mentions that the Department of Health and Human Services (HHS) has initiated “a comprehensive assessment” to investigate autism’s causes, though specifics regarding this assessment remain unclear.

HHS spokesperson Andrew Nixon claimed the website was updated “to reflect gold standard, evidence-based science,” but a subsequent inquiry about the criteria for such a definition did not receive an immediate response.

The timing of this new language is noteworthy, as it precedes the CDC’s vaccine advisory committee meeting on December 4-5, where members are expected to vote on modifications to the childhood hepatitis B vaccine schedule. During a previous meeting, the advisory committee had delayed making recommendations for universal vaccination of newborns against this incurable virus.

The Trump administration had previously pressured the CDC to modify its website, particularly insisting that any references to diversity, equity, and inclusion be removed.

This latest update, as described by Dr. Jesse Goodman, an infectious disease expert at Georgetown University Medical Center and former FDA chief scientist, “crossed the line.” He articulated concerns about the agency being leveraged to disseminate misleading information about vaccines.

Interestingly, the new messaging is not uniform across the entire CDC website. A section aimed at parents maintains that “scientific studies and reviews continue to show no relationship between vaccines and autism.”

However, this revision signals a potential shift in the CDC’s role as an objective source of scientific information.

“In my deepest heart, this is the day CDC died,” lamented a former CDC official who chose to remain anonymous for safety reasons. “The public won’t focus on subtle nuances or different sections of the site. Any communication that attempts to differentiate will come off as tone-deaf.”

The changes on the CDC page appear to contradict Health Secretary Robert F. Kennedy Jr.’s earlier assurances to Senator Bill Cassidy of Louisiana during his confirmation hearing, where he expressed concern that undermining public trust in vaccines could lead to preventable deaths.

A crucial heading on the page still states, “Vaccines do not cause Autism,” but now features an asterisk indicating that the phrasing remains per an agreement with the chair of the U.S. Senate Health, Education, Labor, and Pensions Committee.

One CDC employee remarked about the Cassidy reference as “a direct middle finger” to the senator.

Although Cassidy did not comment publicly, he later stated on social media that “vaccines for measles, polio, hepatitis B and other childhood diseases are safe and effective and will not cause autism. Any contrary assertion is incorrect, irresponsible, and makes Americans sicker.”

Kennedy has a longstanding reputation as an anti-vaccine advocate.

Dr. Amesh Adalja, an infectious disease physician at Johns Hopkins Center for Health Security, mentioned that the website update signals to anti-vaccine proponents that Kennedy remains attentive to their concerns.

What Do the Autism Studies Really Show?

Several experts have accused the CDC of selectively presenting studies that cast doubt on the connection between autism and vaccines, while ignoring credible research that contradicts such claims.

“They’re misrepresenting safety evidence as if it indicates uncertainty. In many ways, that’s worse than citing poor studies because it corrupts the good ones,” criticized Dr. Jake Scott from Stanford Medicine.

For instance, the CDC refers to a significant Danish study from July, indicating that aluminum exposure from vaccines in infants did not correlate with higher rates of neurodevelopmental disorders. In fact, this extensive study involving over 1.2 million children over two decades is viewed as strong evidence against a connection between vaccines and autism.

“If aluminum in vaccines were causing autism or other chronic issues, that study would have shown it,” Scott explained, adding that the findings actually pointed to slightly lower autism rates with increased aluminum exposure.

Nevertheless, the CDC noted a marginally elevated risk of Asperger’s syndrome in a minuscule group, which Scott dismissed as a “statistical blip.”

The webpage also cites two reports from the Institute of Medicine, dating back to 1991 and 2012, which indicated insufficient data to draw conclusions about the pertussis vaccine and autism. “However, those reports actually refuted any links,” Scott clarified.

He further remarked that some studies referenced on the CDC webpage regarding vaccine safety were inadequately conducted.

One example is a 2014 study that suggested a link between aluminum in infant vaccines and rising autism rates. Scott noted that the study merely observed a correlation without establishing causation.

“It’s akin to saying ice cream consumption causes drowning because both surge during summer,” he added.

The CDC also brought up a 2010 study claiming that boys vaccinated for hepatitis B as newborns had a higher autism risk than those vaccinated later or not at all. This study relied on parental surveys, while more reliable records have found no connection, according to Scott.

“They’re not acknowledging the multitude of studies that have found no relationship,” remarked Alycia Halladay, chief science officer at the Autism Science Foundation.

She highlighted the absence of a significant analysis from 2015, which specifically investigated the genetic factors of autism, indicating that the MMR vaccine posed no additional risk, even for children with a family history of the disorder. A comprehensive review from 2021, evaluating 138 studies, also concluded that MMR vaccines do not increase autism risk, but it was not included on the CDC site.

The overall research strongly supports the conclusion for ASF’s Alison Singer: “At some point, we must recognize that this question has been thoroughly answered, much like we no longer debate whether the Earth is flat or round. Enough is enough.”