Egg Allergy and the Flu shot–Updated recommendations

 Trivalent influenza vaccine (TIV) FLU SHOT is safe to use in children with severe egg allergy, and can be given as a single dose, according to research presented at the American College of Allergy, Asthma & Immunology 2011 Annual Scientific Meeting.  I attended this session and the research presented definitely changes recommendations on giving the flu vaccine.

Eggs are delicious: but what about allergy?

This report confirms the recommendation made earlier this year by the Advisory Committee on Immunization Practices (ACIP) and the American Academy of Pediatrics (AAP) — that egg allergy is no longer a contraindication to vaccination with TIV.

Previously, the AAP Red Book considered anaphylaxis to egg or severe egg allergy a contraindication to receiving the vaccine.  When you grow vaccine in egg yolk this is understandable (see below). 

Growing influenza--beware of egg you know why!

“The benefits of flu shots are well established and clearly outweigh the risks for children with egg allergy,” lead author Matthew J. Greenhawt, MD, from the University of Michigan in Ann Arbor, said in a statement. For the full interview, click on this link

“Children with food allergies are more likely to have asthma, which can increase their chance of respiratory complications from the flu. Expanding the population of children who receive flu shots will play an important role in decreasing influenza associated with hospitalization and in promoting the overall health of our children,” he explained.

Using a 2-step approach, the group randomized 28 children who were contraindicated for TIV according to previous AAP Red Book criteria to receive either a 10%/90% split dose of TIV (n = 13), or to receive normal saline plus 100% TIV (n = 15) to mimic the split dose.

In these 28 children, the mean egg skin test wheal was 7.7 mm, mean egg white ImmunoCAP was 23.1 kuA/L, mean ovalbumin ImmunoCAP was 20.4 kuA/L, and mean ovomucoid ImmunoCAP was 18.1 kuA/L.

There were no differences in these values between the 2 groups, Dr. Greenhawt reported.

In addition, they investigators retrospectively analyzed 32 children with severe egg allergy who were vaccinated by their primary care physician despite the contraindication, for comparison.

This retrospective group consisted of 13 children who received TIV as a split dose as a safety precaution and 19 who received it as a single dose. The mean egg white ImmunoCAP was 18.2 kuA/L, and there was no difference between children who received a single or a 2-step split dose of TIV.

None of the children developed an allergic reaction.

“Use of 2-step split dosing appears unnecessary, as a single dose was well tolerated by those who received this either in an allergy clinic or in the primary care setting,” Dr. Greenhawt concluded.

This change in clinical practice probably needs some reassurance!  Todd A. Mahr, MD, director of pediatric allergy/immunology at Gundersen Lutheran Medical Center in La Crosse, Wisconsin, and clinical professor of pediatrics at the University of Wisconsin Medical School in Madison, was comoderator of the session. He told Medscape Medical News that “the nice thing about this paper is that it reaffirms the ACIP and the AAP recommendations that have come out for administration of TIV in egg-allergic patients. This paper was actually submitted before [those recommendations] came out. It is nice to have it at our meeting to reconfirm the new recommendations.”

“What ACIP and AAP say now is that if the patient can eat egg cooked in things, the general practitioner can just go ahead and give TIV and watch the patient for 30 minutes afterwards,” said Dr. Mahr, who was not part of the current study.

Patients with a history of anaphylactic reaction to egg should be sent to a specialist for vaccination. “That specialist can decide what to do. One option is to do a 2-step dosing; another is to give it in 1 dose and be prepared to handle anaphylaxis,” Dr. Mahr said.

Dr. Greenhawt reports financial relationships with Phadia, Sunovion, and Nutricia. Dr. Mahr reports financial relationships with ISTA, Alcon, AstraZeneca, Genentech, GlaxoSmithKline, Merck, and Novartis.

American College of Allergy, Asthma & Immunology (ACAAI) 2011 Annual Scientific Meeting: Abstract 2. Presented November 6, 2011.

#aap-red-book, #advisory-committee-on-immunization-practices, #american-academy-of-pediatrics, #astrazeneca, #egg-allergy, #glaxosmithkline, #gundersen-lutheran-medical-center, #influenza-vaccine

Egg allergy and influenza vaccine

Unfortunately, all influenza vaccines carry the admonition that egg allergic individuals may react to their administration. STOP….before reading any further, make sure you have a true egg allergy before you worry about the influenza vaccine.  Many patients have a positive TEST to eggs, but eat them just fine without any symptoms.  This isn’t an allergy and you have no need to worry about avoiding sunny side up  for breakfast. You do need to still get your flu shot!

There are no exceptions to this since all such vaccines are grown on media which may contain egg allergen. As always, there are clearly alternatives that are available to, in the vast majority of instances, allow the administration of influenza vaccine to egg allergic individuals.  In fact, new guidelines recommend giving the Flu vaccine even if you are allergic to egg….it’s tolerated very well and allergic reactions are quite rare (see below).

That makes me hungry

If you’re concerned, such patients can be tested to egg and influenza vaccine; testing & desensitization is usually highly successful in allowing the safe administration of influenza vaccine under these circumstances.

 Listed below are clinical studies demonstrating that patients with egg allergy can safely receive the influenza vaccine: J Allergy Clin ImmunolVolume 121, Issue 2, Supplement 1, Page S240 (February 2008).

Zeiger RS. Current issues with influenza vaccination in egg allergy. JACI 2002;110:830-40

J Allergy Clin Immunol Volume 123, Issue 2, Supplement, Page S175 (February 2009).

Soooo….how about some history of influenza vaccine? The original injectable influenza vaccine was developed at the University of Michigan in the mid-1940s. The vaccine was made by taking influenza virus, injecting it into embryonated hen’s eggs (see picture), and letting the virus grow in the chorioallantoic cells that surrounded the yolk sac. They harvest the egg, purify the virus, and kill the virus with formaldehyde. I’m sure this is more than anyone wants to know, but since the vaccine was made in eggs, a certain amount of contaminating egg protein, specifically, ovalbumin was always still present.

What do we do, then, about children and adults who are severely allergic to egg proteins? 

1.   During the last 15 years, we have gotten much better at protein purification, protein chemistry, and being able to purify the inactivated virus or the live attenuated virus without using ovalbumin. Thus, there is much, much less ovalbumin in current vaccines. (The quantity of egg protein in vaccine is expressed as the concentration of ovalbumin per dose or unit volume.  Check the package insert to find out if ovalbumin is < 1.4μg/mL; reaction rates are much less below this threshold)

2.  Children with egg allergy can receive the vaccine, but the Advisory Committee on Immunization Practices does recommend that, as a precaution for those who have more severe allergic manifestations like hives (or worse), those children should be given the vaccine in the presence of an allergist or someone who knows what to do should there be an anaphylactic reaction.  I think that’s a good idea.

3.  Ultimately, we will probably give the influenza vaccine much as we give the measles vaccine to children who are egg allergic now. Carefully, but most tolerate both vaccinations just fine.

Want more information–>check out the following resources:

 American Academy of Allergy

Prevention and Control of Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2011. MMWR Morbid Mortal Wkly Rep. [Early release: August 18, 2011.] Available at: Accessed August 22, 2011.

#advisory-committee-on-immunization-practices, #allergy, #egg-allergy, #influenza, #influenza-vaccine