Health Secretary Robert F. Kennedy Jr. has directed the U.S. Centers for Disease Control and Prevention (CDC) to revise its website, which now contradicts its previous assertion that vaccines do not cause autism. This change has alarmed many current and former CDC staff members and raised serious concerns among public health experts about its potential impact on public trust in vaccination programs.

The updated CDC webpage titled "Vaccines and Autism" claims that the assertion "vaccines do not cause autism" lacks definitive evidence, suggesting that health authorities have overlooked studies that may indicate a possible link. This assertion aligns with narratives often promoted by anti-vaccine activists, including Kennedy himself. Interviews with anonymous CDC employees revealed widespread shock and dismay regarding the misinformation presented, with some describing the situation as akin to being on a "hijacked airplane," indicating a loss of control over the agency's messaging.

Public health researchers and advocates have strongly refuted the updated guidance, arguing that it misleads the public by failing to acknowledge decades of rigorous research consistently showing no causal relationship between vaccines and autism. The Autism Science Foundation has emphasized that vaccines have been the subject of extensive study, and no environmental factor has been more thoroughly examined as a potential cause of autism.

Kennedy has acknowledged the existence of studies that demonstrate no link between autism and certain vaccine components, such as the mercury-based preservative thimerosal. However, he contends that gaps remain in vaccine safety science and has called for further investigation. This stance has created tension between Kennedy and Senator Bill Cassidy, a physician and Republican chair of the Senate health committee, who had previously received assurances from Kennedy that the CDC's statement would remain unchanged. Cassidy has publicly criticized the updated guidance, asserting that vaccines for diseases like measles and polio are safe and effective, and that any contrary claims are harmful to public health.

Kennedy's actions as health secretary have included reallocating $500 million intended for vaccine development, replacing members of a federal vaccine advisory committee, and initiating a review of a federal compensation program for vaccine-related injuries. His tenure has raised doubts about vaccination policies, further complicating the public health landscape. Dr. Sean O’Leary, head of the infectious diseases committee at the American Academy of Pediatrics, expressed alarm over the CDC's updated guidance, stating that it perpetuates misinformation and undermines trust in government health communications. The Department of Health and Human Services has not provided additional comments regarding Kennedy's statements or the recent changes to the CDC's website.