What are the benefits of the MMR vaccine?

The MMR vaccine protects your child against three viruses: measles, mumps, and rubella (German measles).

Many parents now choose the MMRV vaccine instead of the MMR. MMRV is the same as MMR, except that it includes protection against the varicella virus, which causes chicken pox.

Measles
Measles is a highly contagious illness that was once almost universal in children. Its main symptoms are a rash, fever, runny nose, cough, and eye irritation.

Possible complications of measles include ear infections, diarrhea, pneumonia, seizures, encephalitis, brain damage, and death.

Before a measles vaccine was licensed in 1964, more than 500,000 cases of measles were reported on average in the United States annually, with about 48,000 hospitalizations and 450 deaths from the disease. After the introduction of the vaccine, the number of measles cases went down 99.9 percent to about 50 cases a year, mostly originating outside the country.

These days, measles has been virtually wiped out in the United States, although a small outbreak is occasionally imported — usually from Europe or Asia — to an unvaccinated population (a group that refuses vaccines, for example) or to people who have received only one dose of the MMR vaccine.

Mumps
Mumps is a viral infection that typically causes a fever, headache, and inflammation of the glands under the jaw.

Mumps can lead to meningitis, encephalitis, and (rarely) deafness. It can also cause painful swelling of the testicles or ovaries. Twenty to 50 percent of males infected with mumps after puberty develop orchitis, an inflammation of one or both testicles. In rare cases, orchitis can lead to sterility.

The current strain of the mumps vaccine has been used worldwide since being approved in the United States in 1967. Before a vaccine was available, the United States had an average of about 150,000 cases every year. In 2003 the number had dropped to 231 — a 99.9 percent decrease in the number of cases. In 2006, however, 6,000 cases were reported to the Centers for Disease Control and Prevention (CDC) during a multistate outbreak.

Rubella, or German measles
Rubella, also called German measles, is characterized by a pinkish red rash that starts on the face, a mild fever, and swollen lymph nodes. It's possible, however, to have rubella without any symptoms.

Rubella is a mild illness that runs its course in about three days, but if a woman gets it during pregnancy, it can cause miscarriage or birth defects in her baby, including deafness, eye problems, heart defects, and mental retardation.

The first rubella vaccines were licensed in 1969. During an epidemic in 1964-1965, 12.5 million cases of rubella were reported in the United States and 20,000 infants were born blind, deaf, or mentally retarded as a result. Today, rubella has been virtually eliminated in the United States, with only a handful of cases reported each year.