The vaccine for children abbreviated by MMR stands for Measles, Mumps, and Rubella. These are the three diseases that the vaccine protects its recipients against. Children generally receive the first dose of this vaccine around 9 to 15 months of age, and then the second dose around 15 months to 6 years of age. There must be at least 4 weeks between doses in order for the vaccine to be most effective.
Measles, mumps, and rubella are all very serious viral diseases; measles is a highly infectious respiratory disease with a red rash that spreads over the body. Mumps affects the saliva-producing (salivary) glands, and rubella also causes a rash and other complications.