Is there a measles-only vaccine for children?

No. This has not been available in the us since the 80's. The MMR was the product of 8 years of additional research after the single vaccine was licensed and reduced the number of vaccines per kid, it is safe and effective.The fraudulent research published by wakefield in 1998 suggesting otherwise was refuted by later research and retracted buy the publisher.Wakefield lost his license over the fraud.