For decades, the U.S. Centers for Disease Control and Prevention (CDC) stood as an unwavering source of scientific clarity, especially on the thorny question of vaccines and autism. But on November 19, 2025, that foundation shook. The agency quietly overhauled a key webpage, replacing its previous unequivocal statement—"vaccines do not cause autism"—with language that now suggests, without evidence, that health authorities might have ignored possible links. The change, first reported by The Wall Street Journal and later scrutinized by Bloomberg and News-Medical.net, has ignited a firestorm among scientists, doctors, and parents, many of whom see it as a dangerous retreat from established science.
The updated CDC webpage now 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 marked shift in tone comes despite decades of research—much of it conducted or endorsed by the CDC itself—showing no credible link between childhood vaccines and autism spectrum disorder. Pediatricians and vaccine experts have long described autism as one of the most studied childhood conditions, with findings consistently debunking any connection to vaccines.
Reaction from the scientific community was swift and severe. "This is madness," Dr. Sean O’Leary, chair of the American Academy of Pediatrics’ infectious diseases committee, told reporters, according to News-Medical.net. "One thing that is very clear is that vaccines are not one of those things. They do not cause autism. Period." The Autism Science Foundation (ASF) echoed that sentiment, calling the new CDC messaging "anti-vaccine rhetoric and outright lies about vaccines and autism." ASF director Alison Singer added, "The idea that vaccines cause autism is not only scientifically false, it’s also profoundly stigmatizing to autistic people and to their families. It frames autism as being caused by parental action, as if autism is a preventable injury."
The controversy has also drawn in high-profile political figures. Health and Human Services Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, has repeatedly claimed—contrary to overwhelming evidence—that vaccines cause autism. According to Bloomberg, Kennedy's views have long been undermined by large-scale Danish studies showing no link whatsoever between autism and various vaccines or their components. Yet, the CDC's new webpage now casts doubt on these very studies, including a widely cited 2002 Danish report previously considered a gold standard by U.S. experts.
Senator Bill Cassidy of Louisiana, who chairs the Senate Health, Education, Labor, and Pensions Committee, had previously secured a commitment from Kennedy during his confirmation hearing that the CDC would not undermine vaccine confidence. Cassidy later posted on X (formerly Twitter), "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." The CDC's revised page retains the heading "Vaccines do not cause Autism"—but now with an asterisk, noting it remains only due to an agreement with Cassidy. One CDC staffer, speaking anonymously, described the reference as "a direct middle finger" to the senator.
The revised language is not consistent across the CDC’s website. While some pages continue to assert that "scientific studies and reviews continue to show no relationship between vaccines and autism," the newly edited page stands in stark contrast, creating confusion for parents and health professionals alike. The CDC’s developmental disability group, a key source of expertise, was not consulted on the changes, according to Abigail Tighe of the National Public Health Coalition.
Scientists and public health officials are particularly alarmed by the CDC's citation of studies that have been widely discredited or misrepresented. For instance, the webpage references a 2014 study suggesting aluminum in vaccines may be associated with a rise in autism cases—a correlation that experts say is no more meaningful than linking ice cream sales to drowning deaths because both rise in summer. It also highlights a 2010 study based on parent surveys, which claimed a threefold higher autism risk in boys vaccinated for hepatitis B as newborns, despite more robust studies using medical records finding no such link. Meanwhile, the page omits a 2015 analysis and a 2021 review of 138 studies, both of which found no connection between the MMR (measles, mumps, and rubella) vaccine and autism.
Many experts see the change as part of a broader political agenda. Dr. Jesse Goodman, former chief scientist at the Food and Drug Administration, told News-Medical.net the administration has "hijacked the premiere public health industry to pursue a narrow agenda of spreading inaccurate information about vaccines." Angela Rasmussen, a virologist and co-editor-in-chief of the journal Vaccine, warned that the revised CDC webpage "will be cited as evidence, even though it's completely invented." The edits, she argued, could be used to justify efforts to roll back recommendations for childhood vaccination—a concern shared by many in the medical community.
Indeed, Kennedy has appointed several longtime anti-vaccine activists and researchers to review vaccine safety at the CDC, with their findings expected soon. His handpicked vaccine advisory committee is scheduled to meet in December 2025 to consider whether to abandon the longstanding recommendation that newborns receive a dose of the hepatitis B vaccine within hours of birth, along with other changes to the CDC's vaccination schedule.
The CDC's credibility has taken a hit, with some former and current staff describing the agency as a "zombie organization" following leadership shakeups and significant staff losses in 2025. "The CDC website has been lobotomized," Atul Gawande, a surgeon at Brigham and Women's Hospital, told KFF Health News. "CDC is now a zombie organization," echoed Demetre Daskalakis, former director of the National Center for Immunization and Respiratory Diseases.
Amid the uproar, leading autism advocacy groups have united in condemnation. The Autism Science Foundation, Autism Society of America, and Autism Self Advocacy Network all issued statements denouncing the CDC's new messaging. "The CDC's web page used to be about how vaccines do not cause autism. Yesterday, they changed it," said ASAN. "It says that there is some proof that vaccines might cause autism. It says that people in charge of public health have been ignoring this proof. These are lies."
Despite the CDC’s new ambiguity, the scientific consensus remains firm. Upward of 25 large studies have shown no link between vaccines and autism, and the hereditary and developmental origins of autism are now well established. As Dr. Bruce Gellin, former director of the National Vaccine Program Office, put it: "There are few examples of science more definitive than the many worldwide studies that have failed to demonstrate that vaccines cause autism."
For worried parents, the confusion sown by the CDC’s revised language may lead to delayed or skipped vaccinations—potentially putting children at risk for preventable diseases. As Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, bluntly stated, "Kennedy thinks he's helping children with autism, but he's doing the opposite."
In a moment when public trust in health institutions is already fragile, the CDC’s about-face on vaccine science has left many wondering if the agency can reclaim its reputation as a beacon of evidence-based guidance. The stakes—for public health, for families, and for the agency itself—could hardly be higher.
