Which allergy constitutes a true hypersensitivity contraindication for the MMR vaccine?

• A. Recent exposure to an infectious disease
• B. Allergy to egg protein
• C. Previous local reaction of fever to a vaccine
• D. Allergy to penicillins

Answer: (B)

The key idea is identifying true contraindications to MMR, meaning hypersensitivities or health conditions that genuinely make vaccination risky. The MMR vaccine does not contain egg protein, so an egg protein allergy does not constitute a true contraindication for this vaccine in otherwise healthy individuals. A genuine contraindication would be a severe allergic reaction to a component actually present in the vaccine (for example, a severe allergy to neomycin, which is a component used in trace amounts in MMR), or conditions that profoundly suppress the immune system, or pregnancy. Other scenarios listed—recent exposure to an infectious disease, a prior local reaction or fever after a previous vaccination, or allergy to penicillin—do not by themselves disqualify someone from receiving MMR, though a moderate to severe acute illness with fever can warrant postponement. In practice, egg allergy is not treated as a contraindication for MMR, and the decision to vaccinate hinges on whether a true vaccine component hypersensitivity or a major health contraindication is present.