Measlesis a viral infection that causes a range of symptoms as benign as rash, fever and eye irritation or more severe, such as pneumonia, seizures, brain damage and death. Mumps is also a viral infection that causes fever, headache, swollen glands, and can cause deafness, meningitis, painful swelling of the testes or ovaries and, rarely, death. Finally, Rubella, also known as German measles, can cause the same viral illnesses, but may result in joint pain as well. If a woman contracts rubella while pregnant, her unborn child may be born with serious birth defects. All three viruses are caused by inhaling affected droplets from a neighboring ill person.
Since 1956, MMR has been required for entry into the US school system; therefore most people born after 1956 should be immunized. Prior to 1956, the assumption is most people were infected with measles, mumps and rubella, and are considered immune. However, if you were born after 1956 and are unsure of your immunity or if you only received one dose prior to entering school, then the series would need to be restarted to ensure immunity prior to travel to endemic countries.
Generally the vaccine is given as two doses: the first at 12-15months old and then at 4-6years old. If you are an adult receiving the series for the first time, or as a booster, the 2 doses can be given 28days apart. If you are traveling to an endemic country with a child <12months old, the MMR vaccine can be given ahead of schedule to give the child some protection prior to travel, though the child would eventually need two more doses for lifetime protection.
The MMR vaccine is a live vaccine; therefore, pregnant women, acutely ill patients, and those with a compromised immune system should not receive the vaccine. Also, people with a neomycin allergy should not receive this vaccine. Reactions to this vaccine are generally mild, including fever, gland swelling and rash; severe reactions include allergic reactions and, incredibly rarely in children, deafness or brain injury.