Food Allergy Resources

By Matthew J. Greenhawt, M.D., M.B.A.

In the wake of the H1N1 pandemic last year, several research groups decided to re-investigate the risk of influenza vaccine, which contains egg protein in the form of ovalbumin, in egg allergic individuals.  For many years, it has been assumed that the residual egg protein poses a potential allergy risk to egg allergic individuals.  Thus, caution has been taken in vaccinating such individuals. Examples of steps taken to reduce the risk of reaction include skin testing to the vaccine, graded/staged dosing and since the late 1990's, use of vaccine that contained less than 1.2 micrograms of ovalbumin/mL.¹   For those with a history of severe reaction to egg, the vaccine is technically contraindicated by the Center for Disease Control and Prevention², the American Academy of Pediatrics³, and the individual vaccine makers, though many allergists have administered influenza vaccine to such patients for  many years, using one of the aforementioned steps to reduce risk. 

With the pandemic and a second influenza vaccine to give last year, three studies examined the safety issues surrounding the influenza vaccine. ^4,5,6 Interestingly, it appears that many past assumptions about the vaccine not being safe for egg allergic individuals may be wrong.  The major findings from these studies included the following:

These were reassuring findings, and have confirmed what many allergists had long suspected — that influenza vaccine was likely safe for those with egg allergy.  On the basis of the recent data from last year, the AAAAI and ACAAI jointly updated the practice parameters on this matter to reflect these findings.⁸

The take home messages are relatively simple.  Foremost, the time to withhold the vaccine from egg allergic patients as a group has passed, and the hope is that this will reduce influenza related illness and complications within the egg allergic population.  Since either a single dose or a two-step graded challenge seems to be sufficient, this gives providers flexibility in choosing a method with which they are comfortable administering the vaccine.  Observation for 30 minutes after being vaccinated is strongly recommended, and providers who chose to vaccinate egg allergic individuals must be prepared to treat anaphylaxis.  Though reactions are rare, they still have occurred, and providers must be prepared.  Another important principle emerging from these studies is that widespread skin testing to the vaccine is not recommended or helpful.

This past year has taught us much about our previous assumptions, and it appears that the vaccine is safe for egg allergic individuals.  While this issue is still being studied, and the concept is still somewhat in evolution, we are hopeful that a once vulnerable population will now begin to receive much needed protection against influenza!

If your child has a history of anaphylaxis to egg, you should discuss with your allergist whether your child should be vaccinated.  While there is evidence that persons with a history of anaphylaxis to egg can and have safely received the vaccine, further study is necessary before the contraindication is lifted.  As well, it is still a matter of debate as to in what setting the vaccine should be given — the primary care setting or the allergist's office.