Some of the vaccine viruses are cultured in chicken embryo fibroblasts, and the products collected contain ovalbumin (OVA) antigens; therefore, egg allergy is a contraindication to OVA-containing vaccination. Children with a history of allergy to eggs have a high rate of allergic reactions to MMR vaccine, which manifest as generalized urticaria, wheezing, respiratory distress, and angioneurotic edema within minutes of vaccination.