“[The MMR vaccine is] bad [and should be split into separate shots].”

Trump's advice is impossible to follow: the separate measles, mumps, and rubella shots are no longer available in the United States. The CDC's own guidance says "single-antigen measles vaccine is not available," and no monovalent measles, mumps or rubella vaccine is approved in the U.S., so no American can follow Trump's advice. There is no evidence the combined MMR vaccine is less safe than separate shots, and the CDC states plainly that "no published scientific evidence shows any benefit in separating the combination MMR vaccine into three individual shots."

The idea that splitting MMR is "safer" traces directly to a fraudulent 1998 study by discredited British physician Andrew Wakefield, which was retracted by The Lancet and which falsely tied MMR to autism. As vaccine expert Dr. Paul Offit of Children's Hospital of Philadelphia notes, there have been "24 separate studies done in seven different countries on three different continents, involving hundreds of thousands of children" proving the vaccine does not raise autism risk. Splitting it cannot reduce a risk that does not exist.

The combined MMR vaccine has been safe and effective since its debut in 1971, and the science is endorsed by the CDC, the American Academy of Pediatrics, and the World Health Organization. Splitting it into three shots gains nothing: it only means more needles, more office visits, and longer windows during which a child is unprotected against measles, mumps, or rubella. "All you're doing is giving a child more shots with no benefit," Offit said. "You're not making it safer."

"All you're doing is giving a child more shots with no benefit. You're not making it safer." — Dr. Paul Offit, vaccine expert, Children's Hospital of Philadelphia