Background: The safety of administering the combined measles-mumps-rubella (MMR) vaccine to patients who are allergic to eggs has been debated for decades because of concern about potential anaphylaxis, since the live attenuated virus used in the vaccine is grown in cultured chick-embryo fibroblasts.
Methods: We recruited 54 children (mean age, 18.5 months) who had not previously been vaccinated and were allergic to eggs. The children's histories of allergy were confirmed with skin tests and double-blind, placebo-controlled food-challenge tests; some children also underwent skin testing with the MMR vaccine. We then routinely administered the vaccine to the children in one subcutaneous (0.5-ml) dose.
Results: All 54 children had positive results on skin testing with egg. Allergy to eggs was confirmed in 26 of the children by convincing histories of anaphylaxis after the ingestion of eggs, in 22 children by food-challenge tests, and in 6 patients by convincing histories of recent allergic reactions occurring after the ingestion of eggs. Of the 17 children who underwent skin testing with the MMR vaccine, 3 had positive results. All 54 children received the MMR vaccine as a single subcutaneous injection; none had an immediate or delayed adverse reaction.
Conclusions: The MMR vaccine can be safely administered in a single dose to children with allergy to eggs, even those with severe hypersensitivity.