MMR is a live vaccine that helps prevent measles, mumps, and rubella in people 12 months of age and older. Typically, it is given as two injections. The second dose is not technically a booster; it is given to provide protection for those who did not completely respond to the first dose. Possible side effects include mild rash, temporary joint pain, and fever.
What Is the MMR Vaccine?The MMR vaccine (officially known as M-M-R® II) is used to provide protection against measles, mumps, and rubella. It is approved for use in individuals 12 months of age and older.
(Click MMR Uses for more information on what the vaccine is used for, including possible off-label uses.)
Thimerosal Content and Other ConcernsMMR does not contain thimerosal (a mercury-containing preservative). People who are concerned about exposure to this substance can be confident that this vaccine has no thimerosal -- not even trace amounts. Some people also are concerned about the aluminum content of vaccines. This vaccine contains no aluminum.
MMR contains animal and human fetal components. Specifically, parts of the vaccine are grown in chick embryo cells, fetal bovine (cow) serum, and a cell line developed from an aborted human fetus.
How Does MMR Work?MMR is a live attenuated vaccine. This means that it contains the living viruses, which have been altered in such a way as to prevent the vaccine from actually causing the diseases. However, the body's immune system still responds to it, providing future protection against infection.
In general, live vaccines provide better protection from infections, compared to other types of vaccines, but can -- in rare cases -- actually cause the diseases, particularly in people who have weakened immune systems.