Purpose of the Study
Although egg allergy is viewed as a contraindication for the administration of the influenza vaccine, this recommendation is based on relatively little data. This study sought to determine the safety of influenza vaccine in patients with egg allergy and to evaluate the value of skin testing with the influenza vaccine before administration.
Eighty-three subjects with egg allergy and 124 control subjects were recruited by the investigators between 1994 and 1997.
The diagnosis of egg allergy was confirmed by history, skin testing, and, if possible, oral challenge. Patients with egg allergy received the vaccine in 2 doses, 30 minutes apart. The first dose was and the second dose was of the recommended dose as determined by age. Controls received one age-appropriate dose of the vaccine. Skin prick tests with the influenza vaccine were performed on all subjects and the content of egg allergen in the vaccines was measured by an inhibition ELISA.
All subjects tolerated the vaccination protocol without any significant allergic reactions. Skin prick tests were positive in 4 subjects with egg allergy and in one control subject. The content of ovalbumin/ovomucoid was 0.1, 1.2, and 0.02 micrograms/mL in the 1994–1995, 1995–1996, and 1996–1997 vaccines, respectively.
Patients with egg allergy can safely receive the influenza vaccine in a 2-dose protocol when the vaccine preparation contains no more than 1.2 μg/mL of egg protein.
Now that the issue of the measles, mumps, rubella (MMR) vaccine and egg allergy has been settled, the authors have taken on the task of answering the same question for the influenza vaccine. Although these results are very encouraging, it is still not possible to provide complete reassurance in this regard (as has essentially been done with the MMR vaccine). Although the MMR vaccine has a single manufacturer and therefore relatively consistent egg content, with the influenza vaccine the authors found that some vaccine preparations (that were not studied in this protocol) contained significantly higher amounts of egg protein (42 μg/mL in one preparation). Therefore, unless the egg content of the specific vaccine is known, caution must still be exercised when it comes to the egg-allergic patient and the flu vaccine.