American Board of Internal Medicine (ABIM) Certification Practice Exam

What reaction must be experienced for an egg-allergic patient to safely receive the inactivated influenza vaccine?

1. Systemic reaction

2. Anaphylaxis

3. Hives

4. Angioedema

The correct answer is: Hives

For an egg-allergic patient to safely receive the inactivated influenza vaccine, a mild, localized reaction, such as hives, indicates that it may still be possible to proceed with vaccination under appropriate medical supervision. This is because the inactivated influenza vaccine has a very low amount of egg protein, and many studies have shown that individuals with a history of egg allergy, especially those who have experienced only hives after consuming eggs, can tolerate the vaccine without significant risk. In contrast, systemic reactions, anaphylaxis, or severe skin reactions like angioedema are concerning, as they signal a higher risk for a serious adverse event. Such reactions would typically necessitate caution or avoidance of the vaccine in favor of potential alternative immunization strategies. Thus, the presence of hives alone allows for the safety and efficacy of administering the vaccine to patients with a history of egg allergy, as long as they are monitored appropriately.