Egg Allergy and the Influenza Vaccine -- A New Perspective

An expert interview with Matthew J. Greenhawt, MD, MBA

Laurie Scudder, DNP, NP

Disclosures

February 18, 2011

In This Article

Recommendations for Administration

Medscape: The report does recommend that providers choose a vaccine with the lowest amount of ovalbumin. One study discussed in the report was noted to have been conducted using "low" ovalbumin-containing vaccine, but the ovalbumin content of vaccine used in other studies is not noted. The ovalbumin content levels of commercially available vaccines are listed in the report and all are ≤ 1 µg. However, 2 products (FluMist® LAIV and Fluzone® TIV) do not list a level. Would you recommend providers not use a product for which the ovalbumin level is unknown? Considering that many providers will be limited in choice of vaccine by formularies, is it safe to use any product with under 1 µg of ovalbumin? How does this amount of ovalbumin compare to amounts in previous years?

Dr. Greenhawt: This is a very complex issue. It has been established for some time that influenza vaccine does contain some residual ovalbumin, and this contamination could potentially provoke an allergic reaction in an egg allergic vaccine recipient. In the past, there was concern that there was a wide variation of ovalbumin content in the vaccines. However, a study from 1998 demonstrated that influenza vaccine containing < 1.2 μg/mL ovalbumin could be safely administered to egg-allergic patients.[7] This important study established a commonly accepted vaccine ovalbumin threshold under which the vaccine could be safely administered to egg-allergic individuals. Recently, many manufacturers have begun to voluntarily list the ovalbumin content of their vaccine, which makes choosing a low ovalbumin-containing vaccine somewhat easier. Not all companies list these values, including Sanofi Pasteur (FluZone and FluMist). However, there are no data demonstrating that concentrations of ovalbumin exceeding 1.2 μg/mL are not well tolerated. Additionally, there is no evidence that egg-allergic patients who have an allergic reaction attributable to their influenza vaccination are, in fact, reacting to the ovalbumin as opposed to another vaccine component. This argument aside, based on the recent year's lot analysis, most lots tested have been below 1.2 μg/mL ovalbumin, so this issue may be moot. However, when available, it is generally advisable that providers use the lowest ovalbumin-containing option that is appropriate for age to further decrease any risk from the procedure.

Medscape: The report also recommends that a person with a history of suspected egg allergy be evaluated by an allergist prior to receiving the influenza vaccine. Is this true even for patients with a non-anaphylactic egg allergy?

Dr. Greenhawt: Yes. Most importantly, before any special precautions are taken, regardless of the severity of egg allergy symptoms reported, it is exceptionally important to verify that the patient is actually egg allergic, and these patients should be referred to a board-certified allergist for evaluation and testing. If the patient is not egg-allergic, then no potential precautions are necessary. The new National Institutes of Health food allergy guidelines emphasize the importance of evaluation by an allergy specialist to make sure that a patient has a valid diagnosis of food allergy, given evidence that many more patients believe that they have a food allergy than actually do.[8]

Medscape: The report strongly recommends that any provider administering vaccines have proper resuscitative equipment available in the office and that all patients receiving a vaccine be observed for some time interval. The message to providers, particularly coupled with data about frequency of reactions in patients with known allergy vs controls, seems to be that caution is required with all patients, not just EA patients. Can you provide some more detail about these recommendations? What is the appropriate time interval for observation? Are recommendations different for patients in different age groups or for those receiving a booster vs those receiving first-time vaccine?

Dr. Greenhawt: There are no evidence-based guidelines to support a waiting period after influenza vaccination to an egg-allergic individual, but we felt that, given that the egg-allergic patient receiving an influenza vaccine is not the typical patient, postinjection observation was important. Although the risk for reaction is low, it is still possible and has been reported in the past. We recommend that any provider who administers influenza vaccine to an egg-allergic individual be prepared to assess and potentially treat an allergic reaction or anaphylaxis. Most allergists who vaccinate their egg-allergic population already have such a procedure and waiting period in place, but many primary care providers who elect to vaccinate their egg-allergic individuals may not have such procedures established. We felt that a 30-minute observation period was sufficient to probably capture any reaction that may happen based on the recommendations used for allergen immunotherapy.

Medscape: Why is it important for an egg-allergic individual to receive a yearly influenza vaccine, despite any potential risk from their egg allergy?

Dr. Greenhawt: Upward of a third of food-allergic children have asthma or allergic rhinitis.[9] Children with asthma who contract influenza are at much higher risk for complications. There is ample evidence that influenza vaccine provides protection to patients with underlying respiratory disease. Although the number of egg-allergic kids in this country likely does not exceed 2%, that is still quite a significant population when you consider that approximately 33% may have asthma or rhinitis, which increases the risk for influenza-induced complications. Thus, providing influenza vaccine for all children, regardless of their egg-allergy status, is important.

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