President Donald Trump said he would be “demanding” drugmakers further split up vaccines into five doses given at six-month intervals, claiming the change would cause “a massive reduction in autism,” according to a Sept. 18 report by The Washington Post. It was not immediately clear which vaccines he was referring to, and the White House did not respond to the Post’s questions on the matter.
President Trump has previously suggested a link between childhood vaccines and autism. Numerous studies have found no association between vaccines and autism. Vaccine experts pushed back on the latest comments, telling the Post there is no new evidence to justify further splitting up doses and that doing so could leave children vulnerable to infectious diseases for longer. José Romero, MD, a former CDC official who consults for the pharmaceutical industry and sits on the American Academy of Pediatrics’ infectious diseases committee, told the Post vaccines “are formulated so that the total dosage that they’re getting is the one that delivers the best immune response.”
The remarks build on an August executive order that called for splitting the combined measles-mumps-rubella vaccine into three separate shots and directed HHS to develop options for administering core childhood vaccines individually rather than in combination. Before the order, President Trump had pressed HHS Secretary Robert F. Kennedy Jr. to further reduce the number of vaccines on the childhood vaccine schedule.
The order followed a September 2025 announcement in which the administration linked autism and ADHD to acetaminophen use during pregnancy, a claim major medical organizations, including the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine, said was not supported by evidence.
