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 19654 reported the safe administration of measles vaccine to 22 children with egg allergy confirmed by food challenges.#### Key messages 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 difficulty following immunisation with measles vaccine.3Serum IgE reactive with ovalbumin related antigens 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 …