replicate (Singh et al., 1994; Pogue et al., 1996). Antibodies to these two self-antigens have been found in the serum of patients with rheumatoid arthritis, an autoimmune disorder (Pogue et al., 1996). Nakhasi hypothesized that when the rubella virus binds to these self-antigens, it changes their shapes such that they are no longer tolerated and can elicit an immune response.
Investigators are assessing whether people given the rubella vaccine develop autoantibodies to the two self-antigens needed for viral replication and whether such autoantibody production is associated with the development of non-rheumatoid arthritis in the long term. Another recent study, however, has not found a correlation between arthritis and rubella vaccination (Slater et al., 1995). A geneticist from the National Institute of Child Health and Human Development (NICHD) suggested assessing whether genetic variation in the genes that code for the two self-antigens to which rubella virus binds might explain differences in susceptibility to arthritic complications of rubella or rubella vaccination.
Anaphylaxis is a life-threatening allergic reaction whose symptoms include itching, hives, low blood pressure, abnormal fluid retention that causes swelling of tissues, and difficulty breathing. According to a report by the Institute of Medicine, the evidence established a causal relation between measles, mumps, and rubella vaccine and anaphylaxis. Estimates of the risk range from 1 per 20,000 to 1 per 1,000,000 per doses distributed (Institute of Medicine, 1994a).
Measles, mumps, and rubella vaccine consists of measles, mumps, and rubella antigens, gelatin, sorbitol, neomycin, and residual egg proteins. Because egg proteins can stimulate an anaphylactic reaction in individuals severely allergic to eggs, it has been assumed that the egg-related antigens in the vaccine were responsible for the rare cases of anaphylaxis that occur following vaccination. Consequently, the American Academy of Pediatrics (AAP) has recommended that children with severe egg allergies be skin tested for allergy to the vaccine. If they test positive, they must then receive a series of allergy shots to desensitize them to the vaccine. It is also recommended that they be observed by trained medical personnel for 20 minutes after vaccination (American Academy of Pediatrics, 1994).
Recent studies suggest that the AAP guidelines may not be appropriate or sufficient. In one study of 224 children with a history of egg allergy, only 29 skin tested positive to measles, mumps, and rubella vaccine. Of these children,