Health Secretary Robert F. Kennedy Jr. has confirmed that he personally directed the Centers for Disease Control and Prevention (CDC) to revise its longstanding vaccine safety webpage, changing the language that previously stated vaccines do not cause autism. His decision reflects a belief that gaps remain in vaccine safety research, particularly concerning infant vaccines given in the first year of life, and indicates a desire for greater transparency and continued scientific inquiry on the matter.
What Kennedy Ordered
Kennedy pointed out that while large-scale epidemiological studies have found no link between vaccines and autism, many of these studies focused on certain vaccines like MMR and thimerosal-containing vaccines but did not comprehensively examine all vaccines given in infancy, such as hepatitis B and the DTP vaccine. He argues that the blanket statement that vaccines do not cause autism is not fully evidence-based because some questions about vaccine safety in vulnerable subpopulations remain unresolved. According to Kennedy, the CDC’s revised webpage language now better reflects this nuance, suggesting that science has not completely ruled out associations and encouraging further study into potential biological or genetic susceptibilities.
Senior health officials say the revision was drafted by political appointees at HHS and transmitted to a small group inside the CDC, which implemented the change midweek without the normal layers of scientific review. The original headline asserting that vaccines do not cause autism remains on the page but now carries an asterisk, with a note explaining that it stayed in place to honor a pledge Kennedy made during his Senate confirmation hearings to preserve that language at the request of Sen. Bill Cassidy, a Louisiana physician who chairs the Senate health committee.
Kennedy’s Rationale
Kennedy, a longtime critic of federal vaccine policy, framed the new wording as an effort to increase transparency rather than to discourage immunization. He has argued that acknowledging uncertainty and re-examining older safety studies will ultimately “drive up vaccine utilization” by convincing skeptical parents that the government is being candid about what is known and unknown.
This unprecedented direct intervention from a health secretary in CDC guidance illustrates Kennedy’s well-known and deeply held skepticism about vaccine safety, which he has championed for decades. He says his decision to alter the website stems from a commitment to being truthful with the public rather than offering reassurances he considers premature or overly simplistic. Kennedy contends that public trust can be strengthened by being honest about scientific uncertainties rather than ignoring parental concerns or dismissing complex issues as “settled.”
Kennedy also conceded that large, well-designed studies have found no link between the measles, mumps, and rubella (MMR) vaccine or mercury-based preservatives and autism, findings that underpin the scientific consensus that vaccines do not cause autism. He contends, however, that questions remain about potential biological mechanisms and cumulative infant vaccine exposure, and has launched a broader HHS review of autism’s causes that he says will revisit data that previous administrations “dismissed.”
Scientific and Political Backlash
While some public health experts and lawmakers have criticized the change as fueling unwarranted fears and undermining vaccination efforts, Kennedy’s supporters argue that acknowledging uncertainty is an essential step toward more personalized vaccine safety research and reforms. He has faced pushback from figures like Senator Bill Cassidy, chair of the Senate Health Committee, who strongly opposes any language casting doubt on vaccine safety but has nevertheless agreed to keep some positive affirmations visible on the CDC website as part of a political compromise.
Inside the federal government, the move has also reopened divisions that surfaced during Kennedy’s contentious confirmation earlier this year. Cassidy, whose support was pivotal to Kennedy’s narrow 52–48 Senate approval, has publicly disagreed with the decision and signaled he may call the secretary to testify about the changes before his committee, setting up a potential showdown between an administration appointee and the Republican physician who helped secure his job.
Implications for CDC and Public Trust
The controversy arrives as the CDC continues to rebuild its reputation after years of political pressure and public confusion over pandemic-era guidance. Current and former agency staffers say the autism-page rewrite is fueling internal anxiety that scientific messaging can again be reshaped from the top down, with little input from career experts.
Kennedy’s directive to change the CDC’s vaccine language should be viewed as part of his broader agenda to scrutinize vaccine safety more closely and prioritize transparency, even if that approach challenges established consensus and creates controversy. His rationale appeals to those who feel that vaccine science must remain open to ongoing questioning and further investigation, particularly regarding potential risks to vulnerable children, while recognizing that this stance has provoked significant debate within the medical and political communities.
