Sir.—The resurgence of childhood measles in the United States has prompted secondary immunization with the measles, mumps, and rubella (MMR) vaccine.1 Immediate allergic reactions to the MMR vaccine, including dyspnea and hypotension, have been documented in egg-allergic individuals.2 Recently, five patients without a history of egg allergy experienced similar reactions, requiring emergency treatment with antihistamines and epinephrine hydrochloride.3 The MMR vaccine contains hydrolyzed gelatin, sorbitol, and neomycin sulfate (25 μg).4 Neomycin is an antibiotic that is known to cause both local and systemic allergic reactions. Our experience with the following patient suggests that hypersensitivity to these additives found in the MMR vaccine, especially neomycin, may be a factor in documented reactions in individuals without egg allergy.
Patient Report.—The patient was a 7-year-old white boy who ingested all food products, including eggs, without incident. His medical history was remarkable for mild asthma treated symptomatically with