Administration of influenza vaccines to egg-allergic patients

In this month’s issue, John Kelso, MD, wrangles with the very important clinical issue of vaccinating patients with egg allergy against influenza. Starting with a review of the Vaccine Adverse Event Reporting System (VAERS) from 1990 to 2005, he finds only 4 reports of deaths that occurred after vaccination and were attributed to anaphylaxis. Approximately 747 million vaccinations were given during the time period. On the down side, about 540,000 deaths from seasonal influenza were reported for the same 15 years. Kelso poses the conundrum: most of those deaths could have been prevented by vaccination, and, in particular, many of them may have been egg-allergic patients.

Two recent JACI publications are addressed in the editorial. The first, a Clinical Pearls article by Rank and Li, recommends vaccination protocols for asthma patients. Specifically, the vaccination protocol for asthma patients with confirmed or suspected egg allergy was conservative and included skin prick testing and intradermal testing of both ovalbumin and influenza vaccine, followed by 2-dose or graded multiple dose vaccine administration. Rank and Li imply the possibility of no vaccination, though this is considered the least desirable approach.

The second article, by Waibel and Gomez, challenges this highly conservative approach, noting previous research establishing that a 2-dose protocol is safe in egg-allergic patients when the vaccine contains ≤ 1.2μg/ml of egg. Manufacturers of vaccines approved by FDA in 2009-2010 state a maximum ovalbumin content of ≤ 1μg/dose, with only one exception reporting greater than that. Since there is more than one vaccine dose, the authors tested lots of H1N1 and/or seasonal flu vaccines from 6 manufacturers to determine the μg/ml ovalbumin content. In all cases, the actual ovalbumin content was lower than the manufacturers stated content, leading Waibel and Gomez to suggest a single dose administration of vaccines with ≤ 1.2μg/ml ovalbumin to egg-allergic patients.

In the editorial, Kelso argues that pre-testing of egg-allergic patients was a good idea when the maximum ovalbumin content was not provided by manufacturers, but in light of safety research and voluntary reporting by manufacturers, these recommendations may be too conservative.

Kelso points out that egg allergic patients react to egg ingestion, but typically not flu vaccination. He suggests there is sufficient clinical and epidemiological evidence to support single dose vaccinations for egg allergic patients, unless the ovalbumin content is not known or if the egg allergy is severe.

We want to hear from you. Please feel free to post your own questions or comments below. All questions and comments will be forwarded to the authors for a response.