Updated: April 21, 2010
Measles is a serious disease caused by a highly contagious virus, which spreads when people touch or breathe in infectious droplets passed by coughing and sneezing. Measles begins with fever followed by cough, runny nose, and conjunctivitis (“pink eye”). Infections of the middle ears, pneumonia, croup, and diarrhea are common complications. Measles encephalitis (an infection of the brain) occurs in 1 per 1,000 cases of natural measles, frequently resulting in permanent brain damage in the survivors. Approximately 5% of children (500 out of 10,000) with measles will develop pneumonia. In addition, 1 to 3 of every 1,000 children who get measles in the United States dies from the disease.
Death is more common in infants, in malnourished children, and among immunocompromised persons, including those with leukemia and HIV infection.
Subacute sclerosing panencephalitis (SSPE) is a rare fatal illness caused by ongoing measles virus infection of the brain. Symptoms of brain damage usually begin 7 to 10 years after infection. Death occurs 1-3 years after the onset of symptoms. Risk factors for developing SSPE include developing measles infection at a young age. The incidence of SSPE is estimated to be between 7-11 cases/100,000 cases of measles. Measles vaccine virus was not associated with SSPE.
Prior to licensure of the first measles vaccine in 1963, virtually every person in the U.S. got the measles by age 20. Since the vaccine became available, there has been a 99% reduction in the incidence of measles. However, measles is still being “imported” from other countries.
Because of intense misinformation about MMR in the United Kingdom, MMR vaccine coverage has declined across Europe, resulting in outbreaks of measles and mumps in multiple countries, including the United States and Canada, and congenital rubella in the Netherlands and Canada. There were 140 cases of measles in the United States in 2008; more than three quarters of these cases were linked to imported measles from another country; most of the cases were unimmunized American children.
The measles vaccine is available as:
Year licensed: 2005
Product: M-M-R II
Year licensed: 1971
Neither MMR or MMRV vaccines contain thimerosal.
The first measles vaccine was licensed for use in the U.S. in 1963. Today, measles vaccine is generally given in combination with mumps and rubella vaccines (MMR) or MMR combined with varicella (MMRV).
Originally, just one dose of MMR vaccine was recommended, and about 90-95% of children were protected. In 1989, the American Academy of Family Physicians, the American Academy of Pediatrics, and the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices changed the recommendation to two doses so that almost all children (99.7%) would be protected.
This change and a higher vaccination rate have nearly eliminated these three diseases in the United States. Continued immunization of children is needed to prevent the spread of measles imported from other countries.
Monovalent measles and rubella vaccines are no longer produced in the United States.
Who should receive the MMR vaccine?
Immunity against measles is particularly important for adults at high risk for measles exposure, including college students and health care workers. People born before 1957 who are not in one of these high-risk categories are generally considered immune to measles through environmental exposure. Women of child bearing age should have immunity to rubella confirmed.
Frequently, it is believed that members of the following groups should not receive the vaccine. In fact, susceptible persons in these categories may receive the vaccine:
Who should not receive the MMR vaccine?
This vaccine is recommended by:
The immunization schedules for children, adolescents and adults can be found at the CDC web site.
Two doses of MMR vaccine administered on or after the first birthday are recommended for all children, including those who previously received the monovalent measles vaccine. The first dose is generally given at 12 to 15 months of age, and the second dose is generally given at four to six years of age. There must be a minimum of four weeks between doses.
Ninety-five percent of those who receive the MMR or monovalent measles vaccine at 12 months of age or older are immune after the first dose. After the second dose, 99.7% of those immunized are protected. Immunity is lifelong.
Nearly all children who get the MMR vaccine (more than 80%) will have no side effects. Most children who have a side effect will have only a mild reaction, such as soreness, redness or swelling where the shot was given, mild rash, mild to moderate fever, swelling of the lymph glands, and temporary pain, stiffness, or temporary swelling in the joints.
In about 5% to 15% of children given MMR, a fever in excess of 103 degrees F may occur—usually beginning about 7 to 12 days after the vaccine has been administered.
About 15% of women who receive MMR will develop acute arthritis or swelling of the joints. This condition is usually very short-lived.
In rare cases (about 3 children out of 10,000 given MMR, or 0.03% of recipients) a moderate reaction such as seizure related to high fever may occur. The risk of a febrile seizure after the first dose of MMRV is increased by an additional child per 1000 (compared to children who got MMR and varicella vaccine at different sites on the same day).
In very rare cases (far less than 1 child out of 10,000 given MMR), children have a serious reaction, such as lowered consciousness, coma, or hypersensitivity (anaphylaxis)—swelling inside the mouth, difficulty breathing, low blood pressure, and rarely, shock. Even more rarely, children may have low blood platelets that can lead to a temporary bleeding problem that is described in more detail in the “Related Issues” section below. Since 1990, there have been 11 case reports of anaphylaxis in those who received the vaccine. Thirty to 40 million children were vaccinated during this time period. No children who experienced such a reaction died as a result.
In extremely rare cases (less than 1 child out of 1,000,000 given measles vaccine) children have developed encephalitis 6-15 days after vaccination.
MMR side effects are largely due to the measles vaccine that it contains. Adverse reactions to the monovalent mumps vaccine are rare.
Reimmunization with MMR vaccine is not associated with an increased incidence of reactions even when a person is already immune to one or more of the viruses.
Students who are exposed to measles who have not already received two doses of the vaccine, and who do not have other proof of immunity, may be excluded from school for the entire duration of the outbreak or be required to receive the measles vaccination. The second dose of the measles vaccine series is effective when given as early as one month after the first dose and this schedule is used when protection is needed quickly.
There has been extensive misinformation about whether measles-containing vaccines might be associated with autism and/or inflammatory bowel disease. These theories have been fully discredited: MMR vaccine does not cause autism.
Researchers estimate that about one in every 22,000 MMR vaccinations could result in a child developing a temporary bleeding disorder called idiopathic thrombocytopenic purpura (ITP). ITP is rarely dangerous— generally much less serious than measles, mumps, or rubella — and is easily treated. A recent study found that children who had ITP and later received the MMR vaccine had no vaccine-associated recurrences.