The "vast majority" of children can safely be given the measles, mumps and rubella (MMR) vaccine regardless of whether they are allergic to eggs, consultants say.
Reporting the results of a literature review in the British Medical Journal (2000;320:929), Dr Gulamabbas Khakoo and Dr Gideon Lack (consultants at the department of paediatric allergy and immunology, St Mary's hospital, London), said: "The MMR vaccine is as safe as any other vaccine, and children with an allergy to eggs must not have their vaccinations delayed." They add that the findings can be applied to any egg-derived vaccine.
However, special precautions should be taken when vaccinating certain children. Dr Khakoo and Dr Lack developed recommendations that have been endorsed by the Committee on Infection and Immunisation of the Royal College of Paediatrics and Child Health, and the British Society of Allergy and Clinical Immunology. These recommend that MMR vaccine should be administered in hospital if a child has cardiorespiratory symptoms after ingestion of egg or if a child has a mild reaction to egg (eg, gastrointestinal symptoms, urticaria) and has active, chronic asthma.
Concerns had been raised over the possible presence of the egg protein, ovalbumin, in vaccines, since the measles virus used is grown in cultures derived from chick embryos, they say. However, they conclude that the amount of ovalbumin in the MMR vaccine seems to be "far too small" to cause an allergic reaction in the majority of individuals, even considering the parenteral route of exposure.
Dr Khakoo and Dr Lack suggest that allergens other than egg may have a role in reported reactions to MMR. This was supported by the fact that a large number of the allergic reactions have occurred in children who are not allergic to eggs. Potential allergens found in the MMR vaccine are neomycin and gelatin which are present at larger doses than ovalbumin, they say.