President Donald Trump's latest executive order calls for splitting the measles, mumps and rubella, or MMR, vaccine into three separate shots, even as doctors and other experts say the move has no scientific basis and is unlikely to get off the ground. Trump on Monday said without evidence that the combined vaccine could be "quite lethal," despite large-scale studies repeatedly proving the shot safe and effective. The order lands squarely on children and parents, while the people making the decision sit far above the consequences.
Who Pays for the Power Play
Roughly 9% of parents report either skipping or delaying the MMR vaccine for their children, according to a 2025 survey conducted by health policy organization KFF and the Washington Post. That hesitation has already fed the recent resurgence in U.S. measles cases, and the U.S. has logged its highest number of measles cases in decades this year. Dr. Andrew Racine, president of the American Academy of Pediatrics, said on Wednesday that Trump's rhetoric and recommendations could further undermine the public's confidence in the safety of the MMR vaccine.
"Why would we not give children a vaccine that is safe, that prevents death?" Racine said. He also noted that two healthy children died in the U.S. from measles last year. Those are the stakes. Not abstract policy. Not a press release. Children, families, and communities are left to absorb the fallout from a top-down stunt dressed up as medicine.
What the Experts Say
Experts called Trump's claim "completely false" and said there is no scientific data showing benefits of separating the shot. Neil Maniar, a public health professor at Northeastern University, said splitting the vaccine would come with "significant logistical limitations," and that three standalone shots requiring multiple doctor's visits could lead to more delayed or missed vaccinations among kids. "They're not solving a problem here. They're creating a new one," Maniar said. "Based on false scientific rationale and political ideology, they're changing something that works into something that we have no idea what it will do."
William Moss, a pediatrician and epidemiological professor at Johns Hopkins University, said he doesn't see the effort having an immediate or short-term impact on the ongoing measles outbreak. Still, he warned that Trump's rhetoric could confuse parents and push more of them to hold off on immunizing their children. The machinery of authority can spread doubt faster than disease control can catch up.
The combined MMR shot is currently given at 12 to 15 months of age, with a second dose at 4 to 6 years of age. Separating the vaccine could result in a child needing to receive six different doses in their early life. Moss called that "just so counterintuitive and counterproductive," adding, "It's ironic when they're claiming that children receive too many shots, and then they turn around and propose a policy that's just going to increase the number of shots they get."
The Bottlenecks Built Into the System
Maniar said a single visit can already be challenging for parents who have to take time off work, and healthcare access is more complicated in certain communities, such as rural areas. He said the U.S. childhood vaccination schedule is designed around both the child's "immune system readiness" for a particular shot and their risk for a certain illness. Spacing out those vaccines could increase the chance of a child missing or delaying a shot for a preventable disease they're at risk for.
Merck and GSK, the manufacturers of the MMR vaccine, seem to have little incentive to develop standalone shots, according to the article. Moss said he doesn't see any world in which vaccine manufacturers would go through the rigorous regulatory process, get FDA approval, and do the trials for monovalent measles, mumps, and rubella vaccines. "It would be a foolish investment to make," he said. AAP's Racine also said it would likely take more than a decade to develop those standalone shots.
In a statement on Wednesday, Merck said evidence suggests using combination shots improves childhood vaccination outcomes, increasing the completion of all recommended doses and compliance rates. That matters because the system already makes access hard enough without adding another layer of delay, another appointment, another hoop for parents to jump through.
The article also notes that it's unclear where Trump initially got the idea to split the shots, though some experts say it can likely be traced to Andrew Wakefield, a British gastroenterologist and anti-vaccine advocate. Wakefield published a paper in 1998 claiming to show a connection between MMR vaccines and an increase in autism. That paper has since been retracted, and Wakefield was removed from the U.K.'s medical register.
A separate fact-check said there is no evidence the combined MMR shot is dangerous and cited decades of safety data supporting its overall safety. It also noted a small risk of febrile seizures after fever associated with vaccines, but said such seizures do not cause long-term harm, citing the Centers for Disease Control and Prevention. The facts are already there. The damage comes from power pretending otherwise.