MMR vaccine. Gloved hand draws MMR vaccine from a bottle into a syringe. The rubber glove helps maintain a sterile environment. The MMR vaccine gives immunity to three diseases: measles, mumps and rubella. It is generally given by injection to infants in their second year. It contains dead or weakened forms of the viruses which cause each disease. When injected, the immune system easily kills the weakened viruses. If the body comes into contact with the viruses again, it remembers how to deal with the infection, and stops it before it becomes serious.