The Brief President Trump signed an executive order to separate the MMR (measles, mumps, rubella) vaccine into three individual shots. It is unclear when or how the change will be implemented, as separate vaccines are not currently available in the U.S.President Donald Trump signed an executive order on Monday that called for spacing out childhood vaccines, and separating the measles, mumps and rubella (MMR) vaccine to be split into three shots. Trump said he believes childhood vaccines should be split up into separate doctor visits. And it gets progressively worse and we add progressively more and more vaccines," President Trump told reporters at the signing Monday. MMR vaccination rates already falling in MinnesotaBy the numbers:MMR vaccination rates have been declining in Minnesota.