Leading articles MMR vaccine and allergy

MMR vaccine and allergy Live measles and mumps vaccine viruses are cultured in chick embryo fibroblasts and may contain minute amounts of egg related antigens. 1–3 In view of this, there has been a longstanding debate on the safety of these vaccines in children with severe allergic reactions to egg. Initially it was believed that such children could safely receive the vaccine; Kamin et al in 1965 4 reported the safe administration of measles vaccine to 22 children with egg allergy confirmed by food challenges. The concern was again raised in 1983 by Herman et al when they reported two children with allergy to egg white protein who had generalised urticaria, angio-oedema, and respiratory diYculty following immunisation with measles vaccine. 3 Serum IgE reactive with ovalbumin related anti-gens in the vaccine was demonstrated in both children. They also showed the presence of ovalbumin reacting protein in the vaccine. They subsequently evaluated 24 children with egg allergy using skin prick testing with ovalbumin and measles vaccine. They found that children with severe reactions to egg were more likely to have a positive skin reaction on testing with the vaccine, and those who had a positive skin test had IgE antibodies reacting to ovalbumin. Non-allergic children had negative skin tests. From this they recommended that patients with severe reactions to egg white should be skin tested with dilute vaccine, first by scratch test and, if this is negative, by intradermal injection. If both were negative, the vaccine could be given as a single dose of 0.5 ml. If either were positive, they recommended that the vaccine be administered in slowly increasing increments of 0.05 ml, every 15 to 20 minutes. The 1991 Red Book published by the American Academy of Pediatrics recommended a similar policy for children with severe reactions to egg. However further evidence suggesting that children allergic to eggs were at no greater risk continued to accumulate. 4A-D By 1995, of 40 reported cases of anaphy-laxis to measles/mumps/rubella (MMR) vaccine given as a single dose, only two involved children with egg allergy (the same two reported by Herman). 1 3 5–10 A review of 17 studies from 1963 to 1995 showed only (the same) two of 1227 patients who were allergic to eggs and had been given the vaccine had developed any symptoms suggestive of anaphylaxis 11 ; this included many children with convincing history of severe allergic reactions to …