Measles / Mumps / Rubella Information
WHO Information Fact Sheet
Combined live vaccine for measles, mumps and rubella (MMR) is used widely for the immunization of children in certain regions of the world because of its advantages over the individual vaccines. Combined vaccine provokes an adequate immune response in children simultaneously for the three infections and facilitates the implementation of current immunization strategies.
Measles is an almost invariable clinical experience of childhood, and is often a severe disease, frequently complicated by middle-ear infection or bronchopneumonia. In some countries it is a major cause of illness and death. Encephalitis occurs in approximately one of every 2000 reported cases; survivors often have permanent brain damage and mental retardation. Death, predominantly from respiratory and neurological causes, occurs in one of every 3000 reported measles cases. The risk of death is greater for infants and adults than for children and adolescents.
Contracting measles during pregnancy increases fetal risk. Most commonly, this risk involves premature labour and moderately increases rates of spontaneous abortion and of low birth weight.
Subacute sclerosing panencephalitis, a slow virus infection of the cental nervous system, is associated with measles virus. It is noteworthy that, in the United States of America, widespread use of measles vaccine has led to the virtual disappearance of this infection.
Immunization against measles has been of interest to WHO for many years, and especially since the Expanded Programme on Immunization was launched in 1974 with measles as one of the principal diseases against which it was directed. In support of the immunization programme, reference materials for anti-measles serum and measles vaccine virus have been established. The Requirements for Measles Vaccine (Live) were adopted by the WHO Expert Committee on Biological Standardization in 1966, with an Addendum in 1981 to include the accelerated test for stability. Since the original production of measles vaccine, the search for improved immunizing agents has continued.
Mumps is an acute disease of children and young adults, caused by a paramyxovirus of which there is only a single serotype. Mumps virus produces no symptons in about one-third of infected people. In those with a clinical response, glandular and nerve tissue are most often affected. The most common signs are fever and swelling of the parotid glands. Other complications, which may appear simultaneously with these signs or in any sequence, are epididymo-orchitis, meningo-encephalitis, cranial nerve involvement (especially eighth cranial nerve damage leading to hearing impairment), pancreatitis, oophoritis, mastitis and myocarditis. Frequent viruria and abnormal renal function suggest that mumps virus may infect the kidneys. In some instances, one or more of the other implications may be present in the absence of parotitis.
The most common complication of mumps in children is meningitis, sometimes associated with encephalitis, and in young adults orchitis. Most complications due to mumps infection resolve without permanent damage. Death following mumps is rare and is mostly due to mumps encephalitis. Many people reach adulthood without developing immunity and potential target populations for immunization therefore include both children and susceptible adults.
The Requirements for Mumps Vaccine (Live) were adopted by the WHO Expert Committee on Biological Standardization in 1992.
Rubella (German measles) gives rise to a mild exanthematous illness, accompanied by few constitutional symptions, and occurs most commonly in childhood. If the infection occurs in a woman in early pregnancy however, the virus may cross the placenta to reach the fetus, in which the infection can induce birth defects. These defects may be serious and permanent and include congenital heart disease, cataract formation, deafness and mental retardation. The prevention of fetal infection, therefore, is the primary purpose of rubella immunization.
To meet the need for an international standard for anti-rubella serum for use in the assay of rubella antibodies and in the control of specific (anti-rubella) immunoglobulins, the WHO Expert Committee on Biological Standardization established the second International Reference Preparation of Anti-Rubella Serum in 1970. The Requirements for Rubella Vaccine (Live) were adopted by the Committee in 1977, with an Addendum in 1992.