Two doses of the measles, mumps, and rubella (MMR) vaccine are recommended for children by doctors as the best way to protect against those diseases.
The MMR vaccine protects your child from measles, a potentially serious disease, as well as mumps and rubella. The vaccine protects your child from getting an uncomfortable rash and high fever from measles and keeps your child from missing school or child care and you from missing work.
The measles vaccine is very effective. Two doses of measles vaccine are about 97% effective at preventing measles if exposed to the virus. One dose is about 93% effective.
Source: CDC: MMR Vaccine Information