Safety of measles-mumps-rubella vaccine (MMR) in patients allergic to eggs

Since the measles and mumps components used in MMR vaccine are grown in cultures of fibroblast from chick embryos, for a long time there have been concerns about the presence of egg protein in the vaccine and the recommendations given to egg allergic patients. We include in this paper our clinical experience vaccinating egg allergic patients with a regular triple viral vaccine, as well as an immunological study of each vaccine available in Spain. The aim of this study was to evaluate the clinical safety of a conventional MMR vaccine in a population of egg allergic patients and to determine the presence of egg allergens in a conventional MMR vaccine and if IgE antibodies from egg allergic can recognize egg allergens in this vaccine.

Children 15 months old with a confirmed diagnosed of egg allergy were included. In all patients, a skin prick test with non diluted MMR vaccine (Priorix, GSK) was made. If negative, each patient received a single dose of measles, mumps, rubella (MMR) vaccine. If positive, a fractionated injection of the vaccine was made following SEICAP recommendations (2004). SDS-PAGE immunoblotting was performed with Priorix vaccine.

A cumulative total of 26 patients with egg allergy have safely received MMR vaccine in a single-dose (after a negative SPT in all cases) at our department without any reaction. 5 sera of vaccinated patients and 6 control sera of egg allergic patients (positive oral challenge) were used to immunolabel the membranes. No positive bands corresponding to egg proteins were found in any of the patients.

Negative results found in SPT support the absence of clinical reaction against the components and Immunological studies point that there is no detectable amount of egg protein in this vaccine to produce an IgE mediated reaction. We can conclude that MMR can be safely administrated in children allergic to egg.