MMR

MMR stands for measles, mumps, and rubella. It is a combined vaccine that protects against three viral diseases caused by distinct viruses. The vaccine uses live attenuated strains to stimulate an immune response without causing the diseases in healthy individuals. It is a core component of routine childhood immunization programs in many countries.

The vaccine is typically given as two doses. The first dose is administered at 12 to 15 months of age, and the second dose at 4 to 6 years. Some regions also offer catch-up vaccination for older children and susceptible adolescents or adults who have not completed the series. In some programs the vaccine is combined with varicella vaccine (MMRV) or given as separate injections.

Effectiveness after two doses is high but varies by disease: measles about 97% protective, mumps around 88–90%, and rubella about 99%. Widespread vaccination reduces transmission and helps achieve herd immunity, lowering the risk of outbreaks and protecting those who cannot be vaccinated.

Safety and contraindications are important considerations. Common side effects are usually mild, such as fever, mild rash, or soreness at the injection site. Rare but serious adverse events can include severe allergic reaction, febrile seizures, or encephalitis. The vaccine is contraindicated in individuals with severe immunodeficiency or pregnancy, and in those with a known severe allergy to a prior dose or to trace amounts of neomycin. Caution is advised during moderate or severe acute illness; vaccination may be postponed.

The MMR vaccine was developed in the late 1960s to early 1970s, with the combined product marketed in the United States in 1971. It has substantially reduced the incidence of measles and rubella and contributed to disease elimination efforts in various regions. Public health authorities emphasize high vaccination coverage to maintain herd protection and counter misinformation about associations with autism.