On November 20, 2025, the U.S. Centers for Disease Control and Prevention (CDC) updated its website to imply that the assertion 'vaccines do not cause autism' is not fully evidence-based. This revision has raised alarms among public health experts, as it contradicts a substantial body of scientific research affirming the safety of vaccines. The updated content suggests that studies supporting a vaccine-autism link have been overlooked by health authorities, a claim that many experts dispute, citing numerous discredited studies and over 40 high-quality studies involving more than 5.6 million participants that have consistently found no causal relationship.

Dr. Susan J. Kressly, president of the American Academy of Pediatrics, criticized the CDC's new statement, emphasizing the potential harm of disseminating misleading information that could erode public trust in vaccinations, which are essential for child health. The CDC's revision also includes a note that the U.S. Department of Health and Human Services (HHS) is conducting a comprehensive assessment of autism causes, including biological mechanisms.

The changes reportedly stemmed from political appointees within HHS, without consultation from relevant CDC staff, raising concerns about the integrity of the agency's scientific communication. Dr. Demetre Daskalakis, who recently resigned as director of the CDC’s National Center on Immunization and Respiratory Diseases, labeled the updates a 'national embarrassment' and expressed worry over the manipulation of scientific information.

Despite the controversy, HHS spokesperson Andrew Nixon defended the CDC's updated position, stating that the claim vaccines do not cause autism lacks comprehensive evidence. Critics argue that this shift aligns with broader trends observed during the Trump administration, which has sought to reshape vaccine policy and foster skepticism towards vaccinations. The CDC's website still contains a header asserting that vaccines do not cause autism, but it is now accompanied by an asterisk referencing an agreement made with Senator Bill Cassidy, who has previously supported controversial figures in the vaccine debate.

Public health experts warn that the CDC's actions could exacerbate vaccine hesitancy and jeopardize public health, particularly as the U.S. faces a resurgence of preventable diseases like measles and whooping cough, with the highest number of measles cases in 25 years. The ongoing debate surrounding vaccine safety and autism highlights the critical need for accurate information to protect public health and maintain confidence in immunization efforts.