The agency replaced longstanding public-health language that vaccines do not cause autism with new wording suggesting the opposite — an unprecedented shift made without scientific review, according to multiple reports.
What Changed and Why It Matters
On November 19, 2025, the Centers for Disease Control and Prevention (CDC) replaced its longstanding Autism and Vaccines webpage with newly revised language that marks a sharp departure from the agency’s prior scientific position.1 The updated page asserts that the statement “vaccines do not cause autism” is “not an evidence-based claim” and argues that existing research has not ruled out the possibility that infant vaccines may contribute to autism. This represents a fundamental shift from the earlier version of the page, which stated plainly that “studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD)” and that no ingredients in routine childhood vaccines had been found to be associated with ASD.2
The sudden reversal immediately drew widespread attention and concern. Reporting across national outlets described alarm among medical experts, pediatric leaders, and public-health organizations, who noted that decades of large-scale studies have consistently failed to identify any causal connection between vaccines and autism.3-5 Several organizations warned that the change risks confusing parents, undermining trust in established immunization programs, and lending credibility to claims long rejected by the scientific and medical communities.
What the New Page Says
The revised Autism and Vaccines webpage begins with a set of key points that fundamentally reframe the agency’s stance on the relationship between childhood vaccination and autism. The page now states that “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,” and it asserts that “studies supporting a link have been ignored by health authorities.” It further explains that the Department of Health and Human Services (HHS) has launched a comprehensive assessment of autism’s causes, including investigations into plausible biologic mechanisms and potential causal links.
Immediately below these points, the page continues to display the longstanding heading “Vaccines do not cause Autism*,” but the accompanying asterisk now redirects readers to an explanatory note. That note states that, “pursuant to the Data Quality Act (DQA), this webpage has been updated because the statement ‘vaccines do not cause autism’ is not an evidence-based claim.” The text reiterates the page’s broader assertion that existing studies have not ruled out the possibility that infant vaccines contribute to autism, and it signals that future updates will incorporate what the agency describes as “gold-standard science” emerging from the new HHS review.
What the CDC Formerly Said
The archived version of the CDC’s Autism and Vaccines webpage, last updated in December 2024,2 presented a clear and unambiguous summary of the scientific consensus that had guided federal vaccine communication for decades. Its Key Points section opened with the statement that “studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD),” followed by the assertion that “no links have been found between any vaccine ingredients and ASD.” These statements reflected a longstanding body of epidemiological research involving millions of children across multiple countries.
The page’s main section, titled “Vaccines do not cause autism,” reiterated that vaccines were not associated with ASD and anchored this conclusion in assessments by the National Academy of Medicine, which described routine vaccines as “very safe.” The archived page also referenced a 2013 CDC study examining antigen exposure in early childhood and reported that children with ASD received no greater cumulative exposure to vaccine antigens than children without ASD, adding to the evidence against any causal relationship.6
A separate section, “Vaccine ingredients do not cause autism,” addressed specific concerns about components such as thimerosal. It stated that “research shows that thimerosal does not cause ASD” and summarized nine CDC-funded or CDC-conducted studies that found no association between thimerosal-containing vaccines or the measles, mumps, and rubella (MMR) vaccine and ASD.
Comparing the Language
The contrast between the archived and current versions of the CDC’s Autism and Vaccines webpage represents a complete inversion of the agency’s prior messaging on vaccine safety and autism. The earlier page stated unequivocally that vaccines showed no link to ASD, reflecting a long-established body of research reviewed and summarized in the agency’s own materials. The new page, by contrast, asserts that saying vaccines do not cause autism is “not evidence-based,” shifting the burden of proof and suggesting that existing studies are insufficient to support the longstanding conclusion.
Where the former page emphasized that no ingredients in childhood vaccines — including thimerosal — had been found to be associated with ASD, the updated version contends that “studies supporting a link have been ignored by health authorities,” implying not only scientific uncertainty but also institutional disregard for purported evidence. This framing reverses a central element of the previous scientific assessment, which consistently reported that extensive research failed to identify any causal connection.
The tone and structure of the two pages also diverge sharply in how they characterize the strength of the evidence. The archived page described a robust scientific consensus grounded in numerous large-scale studies showing no association between vaccines and autism. The new version instead argues that studies have not ruled out a potential causal contribution of infant vaccines, positioning the issue as unsettled and raising questions about biologic mechanisms the agency now proposes to examine through a new federal review process.
Experts React
The revised CDC webpage prompted an immediate and forceful response from medical and public-health experts, many of whom warned that the agency’s new framing contradicts decades of accumulated evidence. In coverage by ABC News, pediatric infectious-disease specialist Paul Offit described the shift as so severe that experts “no longer trust the CDC because they're no longer trustworthy,” adding that the updated page “ignores the data” demonstrating that vaccines — including the MMR vaccine and aluminum-based adjuvants—do not cause autism.3 The same report featured comments from American Academy of Pediatrics (AAP) president Susan Kressly, who noted that more than 40 high-quality studies involving 5.6 million individuals have found no association between vaccination and autism. She emphasized that “the conclusion is clear and unambiguous… there’s no link,” and warned that “anyone repeating this harmful myth is misinformed or intentionally trying to mislead parents.”
Additional reporting raised concerns about how the webpage revision occurred. CBS News described the new language as a “false claim about autism and vaccines,” citing multiple CDC officials who said the update originated with political appointees within HHS rather than with CDC scientific staff.4 The outlet also highlighted the stark contrast between the old and new versions of the page and noted that the Autism Science Foundation characterized the revised wording as “misinformation” that contradicts the best available scientific evidence.
International health authorities also weighed in as journalists sought clarity on the global scientific consensus. Reuters reported that HHS Secretary Robert F. Kennedy Jr. told The New York Times he personally directed the CDC to change its position, confirming the political dimension behind the reversal. In the same report, the European Centre for Disease Prevention and Control reiterated the well-established consensus that, “based on existing evidence, vaccines do not cause autism,” and Reuters noted that the World Health Organization (WHO) and other global agencies have consistently stated that no credible evidence links vaccines to autism.5
Public Health Implications
The reaction from medical organizations and pediatric leaders has centered not only on the scientific inaccuracy of the new CDC language but also on its likely effects on public behavior. Reporting reflects widespread concern that the revised webpage could erode vaccine confidence at a time when maintaining high immunization rates remains essential for preventing outbreaks of measles, pertussis, and other vaccine-preventable illnesses 3,4 Pediatricians warned that parents already grappling with misinformation may view the CDC’s revised language as validation of long-debunked claims, making it more difficult for clinicians to provide evidence-based guidance during routine care.
International health authorities also emphasized systemic risks associated with abandoning well-established scientific conclusions. In statements from the WHO and the European Centre for Disease Prevention and Control (ECDC), both stressed that undoing settled science on vaccine safety threatens to weaken immunization programs and undermine public trust in health institutions. These organizations reiterated that extensive global research demonstrates no link between vaccines and autism and warned that contradicting this evidence could disrupt long-standing public-health progress.5
The potential for misinformation to gain new traction was a central concern among experts interviewed by ABC, who cautioned that the CDC’s revised wording could mislead parents and perpetuate a harmful myth that has repeatedly been disproven through rigorous study.3
What Happens Next
The CDC indicates that the Autism and Vaccines page will not remain static and will instead be revised again as HHS proceeds with what the agency describes as a “comprehensive assessment” of autism’s causes, including potential biologic mechanisms and possible causal links with infant vaccination. The webpage states that future updates will incorporate what it calls “gold-standard science” emerging from that review, though no timeline or methodological details have been provided to date.
In parallel, Reuters reports that Senator Bill Cassidy expressed disagreement with the CDC’s new language, noting that he discussed the changes directly with HHS leadership.5 His comments suggest that congressional scrutiny of the page’s revision process may continue, particularly given the concerns raised about the scientific validity of the new claims and the extent of political involvement.
Fool’s Gold Standard
This revision represents a clear reversal of long-standing, evidence-based language that previously stated childhood vaccines are not associated with autism, replacing it with claims that the agency now considers the prior conclusion “not evidence-based.” Despite this shift, medical experts, pediatric leaders, and global health authorities continue to affirm that extensive research shows vaccines do not cause autism, emphasizing a scientific consensus supported by multiple large-scale studies and reiterated in national and international reporting.
The suggestions that the change may not have originated from CDC scientific staff and instead appears to reflect direction from political leadership within HHS has heightened concern among clinicians, researchers, and advocacy groups, who warn that altering foundational public-health messaging without scientific justification risks undermining public trust in federal health agencies.
Taken together, the abrupt shift in language, the method by which it was carried out, and the strong pushback from the medical community signal a significant inflection point in U.S. vaccine communication. At a moment when misinformation already challenges immunization efforts, the reversal may have far-reaching consequences for how parents interpret evidence, how clinicians counsel families, and how the public perceives the reliability of the nation’s leading public-health institutions.
References
“Vaccines and Autism.” Centers for Disease Control and Prevention. Accessed 21 Nov. 2025.
“Vaccines and Autism.” Centers for Disease Control and Prevention. Accessed 24 Dec. 2024. (via the Wayback Machine.
Kekatos, Mary. “CDC webpage says link between autism and vaccines has been ignored, despite several studies finding no evidence.” ABC News. 20 Nov. 2025.
Breen, Kerry, Michael Kaplan, and Dr. Celine Gounder. “CDC website is changed to include false claim about autism and vaccines.” CBS News. 20 Nov. 2025.
“Kennedy says he told CDC to change website's language on autism and vaccines.” Reuters. 21 Nov. 2025.
DeStefano, F, CS Price,and ES Weintraub. “Increasing exposure to antibody-stimulating proteins and polysaccharides in vaccines is not associated with risk of autism.” The Journal of Pediatrics. 163: 561–567 (2013)
