MMR vaccine
The MMR vaccine is a combined vaccine that protects against measles, mumps, and rubella, usually using weakened live forms of all three viruses.
Live attenuated vaccine: A vaccine made from pathogens weakened so they replicate poorly and usually do not cause disease in healthy recipients. MMR uses weakened live viruses to trigger immunity without causing the usual infections.
Routine childhood immunization schedule: A public-health timetable for giving recommended vaccines during childhood. MMR is routinely given in childhood, with the exact timing set by national guidance.
Measles-mumps-rubella-varicella vaccine: A combined live vaccine that protects against measles, mumps, rubella, and chickenpox. This four-component option adds varicella protection to the three infections covered by MMR.
Herd immunity: Indirect protection from infection that occurs when enough people in a population are immune to limit transmission. High MMR coverage reduces opportunities for these viruses to spread to susceptible people.
Adaptive immune system: The immune system’s targeted defenses, including B cells, T cells, and immunological memory. The vaccine prompts targeted responses and lasting immune memory to its three viral components.
Measles outbreak: A localized rise in measles cases caused by ongoing transmission in a community. Public-health teams may use MMR vaccination to stop transmission and protect susceptible people.
Varicella vaccine: A vaccine that protects against chickenpox caused by varicella-zoster virus. Varicella protection is not included in standard MMR and is given separately or in a four-component vaccine.
Congenital rubella syndrome: A group of birth defects caused when rubella infection during pregnancy harms fetal development. Rubella vaccination reduces infections that can cause this syndrome.
Antibody: A protein made by B cells that binds a specific target, such as a viral protein. MMR-induced antibodies can recognize and help neutralize measles, mumps, and rubella viruses.
Catch-up vaccination: Vaccination given later to people who missed doses recommended earlier in life. People without evidence of immunity may receive MMR outside the routine childhood schedule.