The Centers for Disease Control and Prevention has changed its website to say a link between vaccines and autism “cannot be ruled out,” marking a reversal from the agency’s long-standing position that there is no link. The update has alarmed doctors and public health experts because the claim that vaccines cause autism has been widely debunked by a large body of high-quality research.
Health Secretary Robert F. Kennedy Jr. has long promoted the discredited claim, and the website change comes amid broader shifts at federal health agencies under his leadership. Public health officials warn these moves are undermining confidence in routine childhood immunizations at a time when vaccination rates have fallen and diseases like measles and whooping cough have resurged.
Dr. Susan J. Kressly, president of the American Academy of Pediatrics, said the change promotes false information and called on the CDC to stop amplifying claims that sow doubt about routine immunizations. She noted that since 1998 researchers in seven countries have conducted more than 40 high-quality studies involving over 5.6 million people, concluding there is no link between vaccines and autism.
In a statement to NPR, Department of Health and Human Services spokesperson Andrew Nixon repeated the revised website language: “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.” He said the department has launched a comprehensive assessment of autism causes, including investigations of plausible biological mechanisms and potential causal links.
The Autism Science Foundation criticized the new wording as showing “a lack of understanding of the term ‘evidence,'” adding that no environmental factor has been better studied as a potential cause of autism than vaccines. Dr. Paul Offitt, pediatrician and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, called the language “the usual anti-vaccine tropes, misrepresentation of studies, false equivalence,” and said the phrasing is misleading.
Former CDC official Dr. Demetre Daskalakis said career scientists at the agency were blindsided by the change, noting that scientists did not participate in its creation and that the data underpinning it are unvetted. Two current CDC staffers told NPR the updates are a red flag that vaccine information on the agency website is no longer credible and described the changes as “anti-science.” They spoke anonymously for fear of losing their jobs.
Earlier this year, Kennedy dismissed all members of the CDC’s Advisory Committee on Immunization Practices (ACIP) and replaced them with his own slate. One of the new committee’s first actions was to call for removing thimerosal, a preservative used in a small fraction of flu vaccines, despite longstanding evidence showing no safety problem. The ACIP working group is also studying other major changes, including removing aluminum adjuvants—used for decades to boost vaccine effectiveness—and splitting the combined measles-mumps-rubella vaccine into separate shots. Experts say both moves are scientifically unsound and would upend the childhood vaccination regimen, leaving children vulnerable to diseases long kept under control.
The committee is also considering recommending a delay in vaccinating infants against hepatitis B, a move that would reverse the long-standing practice of vaccinating newborns at birth against a virus that can cause liver failure and cancer.
Under Kennedy, federal efforts have also made it harder for people to get COVID-19 vaccines and cancelled grants funding some new vaccines that rely on mRNA technology. The article notes that the Trump administration has also promoted theories linking acetaminophen (the active ingredient in Tylenol) to autism and promoted using leucovorin, a prescription form of vitamin B9, to treat autism despite scant supporting evidence.
The CDC’s autism-and-vaccines webpage still carries a header reading “Vaccines do not cause autism*” with a footnote saying it has not been removed due to an agreement with the chair of the Senate Health, Education, Labor, and Pensions Committee that it would remain on the CDC website. That chair, Louisiana Republican Sen. Bill Cassidy, who vetted Kennedy’s nomination to lead HHS, posted on X that vaccines for measles, polio, hepatitis B and other childhood diseases “are safe and effective and will not cause autism,” calling any contrary statement “wrong, irresponsible, and actively makes Americans sicker.”
Vaccine proponents warn that the CDC’s website change and the administration’s broader actions are recklessly undermining public confidence in vaccines, fueling hesitancy, and putting children at risk. The U.S. may be poised to lose its status as having eliminated measles if vaccination rates continue to decline.