Donald Trump signed an executive order on Monday that dramatically reshapes official US childhood vaccine guidance, cutting the recommended number of shots from 18 to 11 and calling for the combined measles-mumps-rubella (MMR) jab to be split into three separate doses. Speaking in the Oval Office, Trump claimed that children decades ago received far fewer vaccines and were, in his words, much healthier — and that today's higher autism rates did not exist then. No peer-reviewed evidence supports that link. Multiple large-scale studies, conducted across Europe, Japan, and the United States, have found no connection between the MMR vaccine and autism.

The order carries real-world limits. Because school vaccination requirements are set by individual US states rather than by the federal government, Trump's directive functions as guidance rather than a legal mandate. The 11 vaccines it endorses — covering measles, mumps, rubella, polio, diphtheria, tetanus, pertussis, and four others — remain broadly in line with what most countries already require, but the seven vaccines dropped from federal recommendations could see uptake fall sharply if parents treat the order as official medical advice. The MMR provision drew the sharpest criticism from scientists.

When pressed for evidence that giving the combined shot could be, as he put it, "quite lethal," Trump told reporters: "What I've heard is that there are some people that say it is that way." The Centers for Disease Control and Prevention states plainly that there is no published scientific evidence showing any benefit in separating the MMR into individual doses — and that delays between jabs leave children exposed to disease in the interim.