Just weeks after President Trump said “pure and simple,” vaccines work, he floated a slew of unproven theories linking vaccines to autism, before praising shots in a wide-ranging press conference on Monday.

Why it matters: Trump’s back and forth on vaccines amid consistent science finding them effective risks confusing the public and undermining trust in U.S. medical professionals.

Context: Trump made the remarks during a briefing on autism rates, where he and Health Secretary Robert F. Kennedy Jr. revived a contentious, unproven debate that links autism to acetaminophen, the active ingredient in Tylenol.

What he’s saying: “There are certain groups of people that don’t take vaccines and don’t take any pills, that have no autism,” Trump said during a Monday evening press conference at the White House.

• He repeated the myth that Amish communities have “essentially no autism” and said neither does Cuba, citing “a rumor — and I don’t know if it’s so or not —” that the island nation doesn’t have Tylenol “because they don’t have the money” for the drug.
• The president specifically noted that Americans should be wary of vaccines that include Thimerosal, a mercury-containing compound sometimes used as a preservative in vaccines.

Reality check: While research has found that some Amish people are likely under-vaccinated due to vaccine hesitancy, studies show that some Amish children do have autism.

• A report updated by the Food and Drug administration earlier this year found that a “robust body of peer-reviewed scientific studies” have concluded that Thimerosal is perfectly safe in vaccines.

Of note: At the end of the briefing, the president reversed course, saying that he’s a “big believer” in vaccines because he has “seen how great” and “incredible” they can be.

• Trump said he supports giving kids vaccines to protect against the measles, mumps, rubella and varicella viruses, but added that he disproves of giving them the MMRV vaccine, the combined shot that treats them all.

• Several studies have found no link between MMR vaccination and autism, per a National Institutes of Health post that notes: “Despite strong evidence of its safety, some parents are still hesitant to accept MMR vaccination of their children. Decreasing acceptance of MMR vaccination has led to outbreaks or resurgence of measles.”
• Some doctors already provide separate vaccines for children, but also offer the combined vaccine for parents who wish to reduce the amount of shots their kids must take.

Zoom out: Kennedy’s handpicked vaccine recommendation board voted to limit the availability of the combined shots last week, drawing criticism from public health officials.

Health and Human Services referred Axios to the White House for comment, which did not immediately respond to a Monday evening email request.

Trump backtracks after floating autism-vaccine link

The president called vaccines “incredible” after suggesting they could be linked to autism.

https://www.axios.com/2025/09/23/trump-promotes-unproven-vaccine-theories-then-praises-shots