Pres­i­dent Don­ald Trump fur­ther as­sert­ed con­trol over the na­tion’s child­hood vac­cine sched­ule, call­ing for the measles, mumps and rubel­la (MMR) vac­cine to split in­to three sep­a­rate shots in a new ex­ec­u­tive or­der...