President Donald Trump drew ridicule and alarm after claiming "nothing bad can happen" from his executive order to limit childhood vaccines.
Trump signed the executive order Monday in the Oval Office, calling for the number of diseases vaccinated against to be reduced to 11, according to CNBC.
Decades of scientific research involving more than a million children have found no link between vaccines and autism, according to Autism Speaks.
At Monday's signing, Trump was dismissive of concerns about the order's risks.
"Nothing bad can happen from what we're doing. Nothing bad can happen. We're going to learn a lot," Trump said at the signing.
The reaction from scientists and commentators was swift, with Daniel D. Brown, a senior research scientist at the University of Pittsburgh's Institute for Precision Medicine, among the first to respond.
"He and everyone in this administration is so astoundingly stupid and intellectually incurious," Brown wrote on X.
"Vaccines are overwhelmingly safe. Vaccines are effective. Vaccines DO NOT cause autism," Sen. Bill Cassidy (R-LA), a trained physician, posted on X. "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. This is so wrong."
"A lunatic whose HHS secretary (also a lunatic) caused a measles outbreak signs exec order to dramatically alter childhood vaccine recs," SNY journalist Danny Abriano wrote on X.
"This updated recommendation finally aligns the United States with other advanced and developed nations around the world," Trump said at the signing, according to CNBC. "More importantly, it aligns us with common sense and knowledge."
The order directs Health and Human Services Secretary Robert F. Kennedy Jr. to split the combined measles, mumps and rubella vaccine into three separate shots given on separate visits, CNBC reported.
Health experts have warned that splitting the shot raises the chance of missed visits and skipped immunizations, CNBC reported.
"It's inconvenient, it's five stops, but it's something that I think will have a huge impact on autism," Trump acknowledged after the signing.
Trump signed the order as the U.S. is logging its worst year for measles infections in decades, CNBC reported.
Vaccination rates have fallen since the COVID-19 pandemic, and Kennedy, a longtime vaccine skeptic, has pushed to reshape the childhood shot schedule throughout the Trump administration, CNBC reported.
"Like the polio vaccine, it's amazing. But some — there are questions about — we're going to figure it out," Trump said at the signing.
The order also drew sharp reactions on social media.
"Tell that to all the dead troops," hedge fund founder Spencer Hakimian wrote on X.