Flu Vaccine for People With Egg Allergies

Editor's Note: Don't miss our other reports on the Centers for Disease Control and Prevention's (CDC's) influenza vaccine recommendations for 2016-2017, including No LAIV (Nasal Spray) Flu Vaccine This Season and CDC Provides Vaccine Recommendations for the 2016-2017 Influenza Season. In addition, please visit our Influenza Resource Center often for updates.

I'm Lisa Grohskopf, from CDC's Influenza Division. I am happy to speak with you today as part of the CDC Expert Commentary Series on Medscape. Today, I will be highlighting for you the updated guidelines on egg allergy and receipt of influenza vaccines from CDC and its Advisory Committee on Immunization Practices (ACIP).

Based on the new recommendations:

People with egg allergies no longer need to be observed for an allergic reaction for 30 minutes after receiving a flu vaccine; and
People with a history of severe allergic reaction to egg (ie, any symptom other than hives) can now be vaccinated in a medical setting, under the supervision of a healthcare provider who is able to recognize and manage severe allergic conditions.

Previously, it was recommended that all people with a history of egg allergy be observed for 30 minutes after vaccination and that those with a history of severe allergic reaction to egg be given a flu vaccine only by a physician with experience in managing severe allergic conditions.

Let me start with some background on this issue:

Most flu shots and the nasal spray flu vaccine are manufactured using egg-based technology. Because of this, they contain a small amount of egg proteins, such as ovalbumin. For this reason, in the past there have been precautions surrounding administration of flu vaccine in egg-allergic patients. But more recently, ACIP has reviewed data about the amount of egg protein in flu vaccines as well as the frequency of allergic reactions (specifically anaphylaxis) in people who were given a flu shot.

They found that the amounts of egg protein that are present in most vaccines are sufficiently low that they are unlikely to result in an allergic reaction. Manufacturers who use egg-based production technology and who disclosed the amount of ovalbumin in their vaccines reported maximum amounts of ≤1 µg/0.5-mL dose for flu shots and 0.24 µg/0.2-mL dose for the nasal spray vaccine from 2011-2012 through 2014-2015. Cell-based flu vaccine (Flucelvax®) likely contains a much smaller amount of egg protein because although the original vaccine virus is grown in eggs, mass production of that vaccine does not occur in eggs. Recombinant vaccine (Flublok®) is completely egg free.

Secondly, ACIP looked at instances of anaphylaxis in egg-allergic people and found these to be rare. Flu vaccines do contain various components that may cause allergic reactions, including anaphylaxis, and occasional cases of anaphylaxis in egg-allergic persons have been reported to the Vaccine Adverse Event Reporting System after administration of flu vaccine.

In a Vaccine Safety Datalink study,^[1] there were 10 reported cases of anaphylaxis after more than 7.4 million doses of trivalent inactivated flu vaccine (IIV3) were administered without other vaccines, which translates to a rate of 1.35 per 1 million doses of flu vaccine. It is not known what component of the vaccine caused these reactions. Allergic reactions can occur in response to components of vaccines other than egg proteins.

Given the low levels of egg protein in the flu vaccine and the low likelihood of allergic reactions, for the 2016-2017 flu season, ACIP and CDC have revised the recommendations. CDC has provided an algorithm to guide clinicians through the updated recommendations for flu vaccine and egg-allergic patients this season.

Patients who are able to eat lightly cooked egg (ie, scrambled egg) without reaction are unlikely to be allergic to eggs and can be given any licensed, recommended flu vaccine (ie, any form of IIV or recombinant influenza vaccine [RIV]) that is otherwise appropriate for their age and health status;
Patients with a history of egg allergy who have experienced only hives after exposure to egg also can be given any licensed flu vaccine (ie, any form of IIV or RIV) that is otherwise appropriate for their age and health; and
Patients with a history of more serious reactions to eating eggs or egg-containing foods—those who have had symptoms such as angioedema, respiratory distress, lightheadedness, or recurrent emesis, or who required epinephrine or another emergency medical intervention—also can receive any licensed flu vaccine (ie, any form of IIV or RIV) that is otherwise appropriate for their age and health status, but the vaccine should be given in a medical setting and be supervised by a healthcare provider who is able to recognize and manage severe allergic conditions.

The term "medical setting" refers to hospitals, clinics, health departments, and physician offices. A healthcare provider who is able to recognize and manage severe allergic conditions basically means a healthcare provider who has and can administer epinephrine.

However, some people should not receive flu vaccines, including anyone who has previously experienced a severe allergic reaction to a flu vaccine, regardless of the component suspected of being responsible for the reaction. Flu vaccines contain a variety of components other than egg proteins that can occasionally cause allergic reactions.

Vaccine recommendation updates for the 2016-2017 flu season are covered in a separate Medscape commentary (see Vaccine Recommendations for the 2016-2017 Influenza Season), but a quick reminder: For the 2016-2017 season, ACIP does not recommend live attenuated influenza vaccine, also known as the "nasal spray" flu vaccine.

Thank you for your attention. I will close by reminding you about the importance of your role in protecting the public against influenza. Studies have shown repeatedly that a healthcare provider's recommendation plays a critical role in a patient's decision to receive a seasonal flu vaccine. Please help protect as many people as possible against influenza during the 2016-2017 influenza season by recommending a flu vaccine for everyone aged 6 months and older.

Contact CDC-INFO at 1-800-CDC-INFO or CDCINFO@cdc.gov if you have any questions following today's update.