Senator Bill Cassidy (R-LA), a gastroenterologist and member of the Senate Health, Education, Labor and Pensions Committee, is drawing sharp criticism after condemning President Donald Trump's latest vaccine executive order, despite having voted to confirm Robert F. Kennedy Jr. as Secretary of Health and Human Services.

On Monday, Trump announced a new executive order intended, according to the Associated Press, to "promote his long-held but discredited theory that childhood shots should be spaced out into separate medical visits."

Cassidy, a physician who co-founded a community clinic for uninsured patients in Baton Rouge before entering politics, pushed back forcefully on X. "I'm a doctor," he posted on Monday. "This executive order is wrong. The President does not have the expertise to make these changes. Vaccines are overwhelmingly safe. Vaccines are effective. Vaccines DO NOT cause autism."

He continued: "Breaking up vaccines will mean children have to get more shots to get the same protection, not fewer shots. It will increase hesitancy and make children less safe. Parents should listen to their child's pediatrician about vaccines rather than listening to an inaccurate executive order."

He concluded: "This is so wrong."

The current childhood immunization schedule, maintained by the Centers for Disease Control and Prevention and endorsed by the American Academy of Pediatrics and the American Academy of Family Physicians, is designed to administer vaccines at ages when children's immune systems can respond most effectively and when they are most vulnerable to disease. Decades of research have found no link between vaccines and autism; the claim originates from a since-retracted 1998 study by Andrew Wakefield that was found to be fraudulent.

Because Cassidy cast the deciding vote to confirm Kennedy — a longtime vaccine skeptic who has promoted the debunked autism connection — many on X were quick to highlight what they viewed as his inconsistency. During the confirmation process, Cassidy had cited private assurances from Kennedy that existing vaccine recommendations would remain unchanged as the basis for his support.

NOTUS columnist Matt Lewis wrote: "If only someone could have predicted that the assurances to secure your confirmation votes were BS…"

NBC journalist Garrett Haake noted: "Senator Bill Cassidy — a medical doctor and liver disease specialist — cast the deciding vote to confirm [Secretary Kennedy] and spoke on the floor about the assurances he received that Kennedy — and the admin — would not change existing vaccine recommendations."

The conservative group Republicans Against Trump posted: "You voted for RFK Jr. despite knowing full well he's an anti-vaxxer, conspiracy theorist crank. You emboldened Trump to go even further with his insane and corrupt agenda when you voted Saturday to confirm Todd Blanche, his former lawyer, as attorney general. You own this mess."

Attorney George Conway, a former Republican and ex-husband of Trump's former counselor Kellyanne Conway, remarked that Cassidy is "back to pretending he has a backbone today because the other day everyone said he didn't because he doesn't. Just wait'll tomorrow."

Pradheep J. Shanker, M.D., a contributor to National Review, was more blunt: "This EO is your political epitaph," he wrote.

The clash also underscores a broader tension within the GOP over vaccine policy and public health: Cassidy, who represents a state that has experienced measles outbreaks linked to declining vaccination rates, has positioned himself as a pro-vaccine voice within a party where skepticism toward public health institutions has grown. The CDC reported in 2024 that national kindergarten vaccination coverage for key diseases remained below pre-pandemic levels.

In a 2023 interview with Salon, Zoe Gross, director of Advocacy at the Autistic Self-Advocacy Network, warned that rhetoric from Trump and Kennedy linking vaccines to autism is both scientifically baseless and discriminatory.

"It increases vaccine hesitancy and people choosing not to give their kids vaccines, and that increases the resurgence of vaccine preventable diseases," Gross told Salon. "The other reason is that there's a lot of ableism and anti-autistic sentiment involved in the anti-vaxxer movement, and this lie that vaccines cause autism. You can see that these are people who would rather have their kids get vaccine-preventable diseases and potentially die than do something that they think erroneously risks their kids becoming autistic. That's a pretty bleak view of autism."