Cassidy Warns Against Undermining Vaccine Science After CDC Revises Autism Guidance

Sen. Bill Cassidy (R-La.), a physician and chair of the Senate Health, Education, Labor and Pensions (HELP) Committee, warned Sunday that efforts to weaken public confidence in vaccines pose a public-health risk. His comments came days after the Centers for Disease Control and Prevention (CDC) revised language on its website about vaccines and autism.

What changed at the CDC

The CDC updated a page on autism and vaccines to note that the blanket statement "vaccines do not cause autism" is "not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism." The page also says studies that support a link "have been ignored by health authorities" and notes that the Department of Health and Human Services (HHS), under Secretary Robert F. Kennedy Jr., is conducting a "comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links."

Cassidy's response

On CNN's "State of the Union," Cassidy said that anything that erodes the "absolute scientifically based understanding that vaccines are safe" creates a problem for public health. He urged people to consult their physicians and to rely on the scientific consensus.

"The fact is, the scientific community agrees that vaccines are safe. Talk to your physician. Keep your family safe. Don’t be misled," Cassidy said.

Cassidy also said the CDC added an asterisk to a section titled "Vaccines do not cause Autism" after a conversation he had with former President Donald Trump, though he did not provide further details about that exchange.

Scientific context and policy developments

Decades of research have found no causal link between routine childhood vaccines and autism. A literature review published in August 2022 concluded there is "no link" between autism development and immunization against measles, mumps and rubella (MMR) and other routine vaccines, and recommended that public-health officials continue to promote vaccination.

Despite the established consensus, Secretary Kennedy has for years expressed concerns about a possible connection between childhood vaccination and autism. During his January confirmation hearing before the HELP Committee, Kennedy said he would accept credible scientific evidence if it showed no link. Cassidy, who raised concerns about Kennedy's views, ultimately voted to confirm him in February.

Funding and oversight

Since the change in leadership at HHS, the department has cut more than $500 million in contracts related to mRNA vaccine research — a decision Cassidy pressed Kennedy on during a September hearing. Cassidy said he remains focused on ensuring public safety and the integrity of vaccine science.

Takeaway: Cassidy emphasized that the prevailing scientific evidence supports vaccine safety and urged the public to discuss vaccination with their health care providers rather than rely on mixed messages that could undermine public trust.