Trump's MMR split order faces expert pushback

President Donald Trump has signed an executive order seeking to split the combined measles, mumps, and rubella (MMR) vaccine into three separate shots, claiming without evidence that the combined form could be "quite lethal." Experts across medicine and public health have rejected the premise, citing decades of safety data and warning that the move could undermine vaccination efforts.

Expert reaction

Doctors and scientists called Trump's claim "completely false" and noted that the MMR vaccine has been proven safe and effective in hundreds of millions of doses since its approval in 1971 Source: CNBC. Dr. Walter Orenstein, former director of the U.S. Immunization Program, said splitting the vaccine would require six doctor visits instead of two, "likely lead[ing] to drops in immunization coverage which could lead to major resurgences of the diseases" Source: PolitiFact. Neil Maniar, a public health professor at Northeastern University, said, "They're not solving a problem here. They're creating a new one" Source: CNBC.

Rising measles cases

The order comes amid a resurgence of measles in the U.S., with cases in 2026 already exceeding the total for all of 2025 Source: PolitiFact. Vaccination rates have declined, and a 2025 KFF/Washington Post survey found that roughly 9% of parents report skipping or delaying the MMR vaccine for their children Source: CNBC. Dr. Andrew Racine, president of the American Academy of Pediatrics, linked the drop in vaccination to the recent rise in cases Source: CNBC.

No evidence for split

Trump offered no evidence for his claim, saying, "I've heard when you put them together, they can be explosive" Source: PolitiFact. The White House did not provide evidence, with spokesperson Kush Desai saying Trump wants to "give parents options" Source: PolitiFact. Experts trace the idea to Andrew Wakefield, a discredited British gastroenterologist whose 1998 paper linking MMR to autism was retracted Source: CNBC.