MMR vaccine is a combined vaccine to protect children against measles , mumps , and rubella , which are dangerous and potentially deadly diseases. Alternative names are rubella vaccination , mumps vaccination, vaccine-MMR.
The MMR, which does not contain mercury, consists of live viruses that have been weakened (attenuated) so that the vaccine is still capable of inducing a productive immune response but does not cause the disease that the original or "wild-type" viruses can. The MMR vaccine is a mix of three vaccines: attenuvax (measles), mumpsvax (mumps), and meruvax II (rubella).
The three-in-one MMR vaccine protects against measles, mumps, and rubella. Although single antigen (individual) vaccines are available for each part of the MMR, they are only used in specific situations, in which one of the three diseases occurs and public health officials decide to immunize infants six to 15 months of age for that particular disease. (Single antigen vaccines pose less risk to children younger than the recommended age of 15 months for the MMR.)
Before vaccination, epidemics of measles peaked in the spring every two to four years. Measles is an endemic disease in many undeveloped countries and in countries where measles immunization levels are low. Because the risk of contracting measles in other countries is greater than in the United States, infants and children should be as well protected as possible before traveling.
Measles is caused by a virus that grows in the nose, mouth, throat, and the eyes, and in their secretions. It is highly communicable and may not be recognized early because the symptoms often resemble cold symptoms. The incubation period is 10 to 11 days. Measles begins with slight temperature rise and a runny nose and eyes. About the second or third day, blush-white pinpoint spots with a red rim, known as Koplick's spots, appear in the mouth. Small dark red pimples appear on the head and spread gradually over the body. These pimples grow larger and in groups, giving a blotchy appearance, which is an important difference between measles and scarlet fever . In scarlet fever, the skin appears red all over.
The respiratory symptoms grow worse. The child sneezes often, the eyes are sore, and nasal secretion becomes purulent. Light hurts the eyes (photophobia). The child's throat is sore. The rash is greatest about the fourth day, and it may last up to ten days. During the second week, the skin begins to flake off, and it continues to do so for five to ten days.
Treatment is limited to combating the symptoms of measles because antiviral drugs as of 2004 are ineffective. The disease has serious possible complications. For example, encephalomyelitis (inflammation of the brain and spinal cord) occurs in one to two cases out of 1000 patients; the disease is fatal at that same rate. Immune globulin injections help prevent or reduce measles infection if given within six days of exposure. Complications can be brought on by measles. Encephalitis occurs in one out of 6000 cases; 20 percent of these infections are fatal. Thrombocytopenic purpura (skin hemorrhages because of decreased platelet count ) occur in one out of 3000 cases.
Mumps (epidemic parotitis)
Mumps, another viral disease, affects the salivary glands, especially the parotid gland. Children under the age of two years old seldom have mumps; adults rarely have this disease. A closer contact is necessary to transmit mumps than other contagious diseases. The incubation period lasts from two to three weeks, averaging about 18 days.
In most cases, the first sign of mumps is a swelling in the parotid glands; occasionally, mumps may begin with a slight fever, headache , and malaise before the swelling appears. Sometimes only one of the parotid glands is affected, but both may be inflamed at the same time or one after the other. The glands become swollen and tender and are painful. It hurts for the child to suck while nursing or in older children to open his mouth and eat, but otherwise he may not feel sick at all. After two or three days, the swelling begins to go down, and usually disappears by the tenth day. As a rule, keeping children isolated or out of school for two weeks is long enough to prevent communicating the infection to others. Treatment is entirely palliative; as of 2004, there was no effective antiviral treatment.
Mumps can cause certain complications. The nervous system is affected in 65 percent of patients; 10 percent display symptoms of this, and 2 percent of these cases are fatal. Testicular complications occur in 14 to 35 percent of post-pubertal boys, and complications regarding the ovaries in 7 percent of post-pubertal females. These complications are rare in prepubescent children, however. Deafness in one or both ears occurs in one out of 15,000 cases. More than half of the deaths from mumps occur in those over 19 years of age. Mumps infection during the first trimester of pregnancy increases the risk of spontaneous abortion.
Rubella (German measles)
Rubella is also caused by a virus, but the disease is mild and last only a short time. The symptoms are like measles but are not nearly as severe, and spots never appear on the mucous membranes of the mouth. Sometimes the rash that appears on the face is the first noticeable sign of a rubella infection. The rash spreads quickly and disappears just as rapidly; sometimes it is gone from the face and the neck by the time it reaches the arms and the legs. The rash usually lasts two to four days.
Isolation from other children is brief or not carried out at all; since the infectious stage is so brief, there is little danger of passing on the infection after the rash appears. The greatest risk of German measles is fetal malformations which occur when a mother is infected in the early months of pregnancy.
Children and adults may can have rubella more than once; 3 to 10 percent of those who have had rubella and 14 to 18 percent of those immunized become infected on exposure to the virus. Some reinfections are subclinical (i.e., have no visible symptoms). In fact, some 25 to 50 percent of rubella infections are asymptomatic.
Recommended MMR vaccination schedule
Because the risk of serious disease from infection with either mumps or rubella in infants is low, mumps and rubella vaccines should not be given to infants younger than 12 months old. When the measles vaccine is needed a single-antigen measles vaccine is given. However, parents of an infant less than 12 months of age should be immune to mumps and rubella so they will not expose the infant or become infected if the infant becomes ill.
The first dose of the vaccine is given to children 12 to 15 months old. The second dose of the MMR vaccine should be given at four to six years of age. All children are to be fully immunized before starting school in the United States. Children who have not the second dose as recommended should complete the immunization by 11 or 12 years of age.
MMR traveling recommendations
Before infants and children of 12 months of age or older leave the United States, they should receive two doses of MMR vaccine separated by at least 28 days, with the first dose given on their birthday. Infants under 12 months of age should receive a dose of monovalent (single antigen) measles vaccine before departure. If monovalent vaccine is not available, no specific contraindication exists to giving MMR to infants six to eleven months of age. The risk for serious disease from either mumps or rubella infection among infants is low.
Infants who receive the monovalent measles vaccine or MMR before their first birthday are vulnerable to all three diseases and should be revaccinated with two doses of MMR. The first should be given when the infant is 12 to 15 months of age (12 months if the infant remains in an area where disease risk is high) and the second at least 28 days later.
Parents or adults who travel or live abroad with infants less than 12 months old should have evidence of immunity to rubella and mumps, as well as measles, to avoid becoming infected if the infants are exposed to the diseases.
An infant less than six months of age is usually protected against measles, mumps, and rubella by maternal antibodies. As a rule, the infant does not need added protection unless the mother is diagnosed with measles.
Maternal immunity to MMR
Most fetuses receive some natural immunity to measles from their mothers in utero. This passive immunity fades over time and is less effective in children of immunized mothers than in children of mothers who had the measles.
The duration of protection is dependent to a great extent on the maternal antibody titer and the antibodies received by the infant during pregnancy. Women who have had the disease have higher measles antibody titers than women who have not had measles but have been vaccinated. Women who have not had measles nor vaccination have no measles antibodies.
There are few reasons not to be vaccinated. Some of these are as follows:
- being allergic to gelatin or neomycin or having had an allergic reaction to a previous MMR vaccination
- being moderately or severely ill
- being pregnant
- in males, mumps can cause inflammation of the testes; in female, the ovaries, external genitals, or breasts may be affected
Most of the time inactivated vaccines are given intramuscularly (IM), and live virus vaccines are given subcutaneously (SC). Vaccines that are used intramuscularly may cause local reactions (such as irritation, skin discoloration, inflammation, and granuloma formation) if injected into subcutaneous tissue. The vaccine may also be less effective if it is not given by the proper route.
There is varying incidence of vaccine reactions. Some of these are as follows:
- fever (one out of six)
- mild rash (one out of 20)
- swollen glands (rare)
- seizure (one out of 3,000)
- pain and joint stiffness (one out of 20)
- low platelet count (one out of 30,000)
- serious allergic reaction (less than one out of 1,000,000)
Acellular —Without whole cells. An acellular vaccine contains on parts of the cells which can produce immunity in a person receiving the vaccine.
Active immunity —Produced by the body when the immune system is triggered to produce antibodies, either by immunization or a disease.
Adverse effect —A negative side effect of a vaccine.
Anaphylaxis —Also called anaphylactic shock; a severe allergic reaction characterized by airway constriction, tissue swelling, and lowered blood pressure.
Encephalitis —Inflammation of the brain, usually caused by a virus. The inflammation may interfere with normal brain function and may cause seizures, sleepiness, confusion, personality changes, weakness in one or more parts of the body, and even coma.
Incubation period —The time period between exposure to an infectious agent, such as a virus or bacteria, and the appearance of symptoms of illness. Also called the latent period.
Inflammation —Pain, redness, swelling, and heat that develop in response to tissue irritation or injury. It usually is caused by the immune system's response to the body's contact with a foreign substance, such as an allergen or pathogen.
Passive immunity —The body reception of proteins that act as antibodies instead of making the antibodies itself. Immunoglobulins may produce this immunity. All babies have antibodies from their mothers, which give them short-term protection.
Parents often express concern about combining three vaccines in one injection. As of 2004 there is no published evidence showing a benefit to separating the combination MMR vaccine into three individual shots. The CDC continues to recommend two doses of the combined MMR vaccine for all children.
Because signs of autism may appear around the time children receive the MMR vaccine, some parents worry that the vaccine causes autism. Research has not found a relationship between MMR vaccine and autism.
It is sometimes difficult for parents to adhere to the recommended vaccine schedule, including the spacing between doses. If the intervals between doses is longer than usual, there is no need to restart the series of any vaccine.
MMR vaccinations are appropriate for children with chronic diseases such as diabetes and cardiovascular condition as advised by the pediatrician.
Symptoms of low-grade fever, irritability, and soreness at the injection site following the MMR immunization can be relieved with an analgesic such as acetaminophen as recommended by the pediatrician. Cool compresses to the injection site are also comforting.
Behrman, Richard E., et al., eds. Nelson Textbook of Pediatrics , 16th ed. Philadelphia: Saunders, 2000.
Horton, Richard. A Jab in the Dark: Anxiety and Rationality in the MMR Controversy. New York: New York Review of Books, 2005.
"Childhood Immunization Support Program." American Academy of Pediatrics. Available online at http://www.cispimmunize.org/ (accessed December 18, 2004).
Aliene Linwood, R.N., DPA, FACHE