Flu Vaccine and People with Egg Allergies

Summary:

CDC and its Advisory Committee on Immunization Practices have not changed their recommendations regarding egg allergy and receipt of influenza (flu) vaccines. The recommendations remain the same as last season (2018-2019). Based on those recommendations, people with egg allergies no longer need to be observed for an allergic reaction for 30 minutes after receiving a flu vaccine. People with a history of egg allergy of any severity should receive any licensed, recommended, and age-appropriate influenza vaccine. Those who have a history of severe allergic reaction to egg (i.e., any symptom other than hives) should be vaccinated in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions.

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. However, studies that have examined the use of both the nasal spray vaccine and flu shots in egg-allergic and non-egg-allergic patients indicate that severe allergic reactions in people with egg allergies are unlikely. A recent CDC study found the rate of anaphylaxis after all vaccines is 1.31 per one million vaccine doses given.

For the 2019-2020 flu season, there are two vaccines licensed for use that are manufactured without the use of eggs and are considered egg-free:

Changes:

Recommendations for flu vaccination of persons with egg allergy have not changed since the 2018-2019 flu season. CDC recommends:

  • Persons with a history of egg allergy who have experienced only hives after exposure to egg should receive flu vaccine. Any licensed and recommended flu vaccine (i.e., any form of IIV or RIV) that is otherwise appropriate for the recipient’s age and health status may be used.
  • Persons who report having had reactions to egg involving symptoms other than hives, such as angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who required epinephrine or another emergency medical intervention, may similarly receive any licensed and recommended flu vaccine (i.e., any form of IIV or RIV) that is otherwise appropriate for the recipient’s age and health status. The selected vaccine should be administered in an inpatient or outpatient medical setting (including, but not necessarily limited to hospitals, clinics, health departments, and physician offices). Vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic conditions.
  • A previous severe allergic reaction to flu vaccine, regardless of the component suspected of being responsible for the reaction, is a contraindication to future receipt of the vaccine.

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Questions & Answers:

What is considered an egg allergy? What are the signs and symptoms of an egg allergic reaction?   

Persons who are able to eat lightly cooked egg (e.g., scrambled egg) without a reaction are unlikely to be allergic. Egg-allergic persons might tolerate egg in baked products (e.g., bread or cake). Tolerance to egg-containing foods does not exclude the possibility of egg allergy. Egg allergy can be confirmed by a consistent medical history of adverse reactions to eggs and egg-containing foods, plus skin or blood testing for immunoglobulin E directed against egg proteins.

How common is egg allergy in children and adults?

Egg allergy affects about 1.3 % of all children and 0.2 % of all adults.

What vaccine should I get if I am egg allergic, but I can eat lightly cooked eggs?

If you are able to eat lightly cooked egg (e.g., scrambled egg) without reaction, you are unlikely to have an egg allergy and can get any licensed flu vaccine (i.e., any form of IIV, LAIV, or RIV) that is otherwise appropriate for your age and health status.

What flu vaccine should I get if I get hives after eating egg-containing foods?

If you are someone with a history of egg allergy, who has experienced only hives after exposure to egg, you can get any licensed flu vaccine (i.e., any form of IIV, LAIV, or RIV) that is otherwise appropriate for your age and health.

What kind of flu vaccine should I get if I have more serious reactions to eating eggs or egg-containing foods like cardiovascular changes or a reaction requiring epinephrine?

If you are someone who has more serious reactions to eating eggs or egg-containing foods, like angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who required epinephrine or another emergency medical intervention, you can get any licensed flu vaccine (i.e., any form of IIV, LAIV, or RIV) that is otherwise appropriate for your age and health status, but the vaccine should be given in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions.

Are there still people with egg allergies who should not get flu vaccine?

People with egg allergy can receive flu vaccines according to the recommendations above. A person who has previously experienced a severe allergic reaction to flu vaccine, regardless of the component suspected of being responsible for the reaction, should not get a flu vaccine again.

Why do flu vaccines contain egg protein?

Most flu vaccines today are produced using an egg-based manufacturing process and thus contain a small amount of egg protein called ovalbumin.

For the 2019-2020 flu season, there are two vaccines licensed for use that are manufactured without the use of eggs and are considered egg-free:

  • Flublok Quadrivalent (licensed for use in adults 18 years and older)
  • Flucelvax Quadrivalent (licensed for use in people 4 years and older)

How much egg protein is in flu vaccine?

While not all manufacturers disclose the amount of ovalbumin in their vaccines, those that did from 2011–12 through 2014–15 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. Recombinant vaccine (Flublok Quadrivalent) and cell-based vaccine (Flucelvax Quadrivalent) are the only vaccines currently available that are completely egg free.

Can egg protein in flu vaccine cause allergic reactions in persons with a history of egg allergy?

Yes, allergic reactions can happen, but they occur very rarely with the flu vaccines available in the United States today. Occasional cases of anaphylaxis, a severe life-threatening reaction that involves multiple organ systems and can progress rapidly, in egg-allergic persons have been reported to the Vaccine Adverse Event Reporting System (VAERS) after administration of flu vaccine. Flu vaccines contain various components that may cause allergic reactions, including anaphylaxis. In a Vaccine Safety Datalink study, there were 10 cases of anaphylaxis after more than 7.4 million doses of inactivated flu vaccine, trivalent (IIV3) given without other vaccines, (rate of 1.35 per one million doses). Most of these cases of anaphylaxis were not related to the egg protein present in the vaccine. CDC and the Advisory Committee on Immunization Practices continue to review available data regarding anaphylaxis cases following flu vaccines.

How long after flu vaccination does a reaction occur in persons with a history of egg allergy?

Allergic reactions can begin very soon after vaccination. However, the onset of symptoms is sometimes delayed. In a Vaccine Safety Datalink study of more than 25.1 million doses of vaccines of various types given to children and adults over 3 years, only 33 people had anaphylaxis. Of patients with a documented time to onset of symptoms, eight cases had onset within 30 minutes of vaccination, while in another 21 cases, symptoms were delayed more than 30 minutes following vaccination, including one case with symptom onset on the following day.

 

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Egg Allergy Algorithm

Severe allergic reactions to vaccines, although rare, can occur at any time, despite a recipient’s allergy history. Therefore, all vaccine providers should be familiar with the office emergency plan, and be certified in cardiopulmonary resuscitation. For persons who report a history of egg allergy, ACIP recommends the following (based upon the recipient’s previous symptoms after exposure to egg):

  • Persons with a history of egg allergy who have experienced only urticaria (hives) after exposure to egg should receive influenza vaccine. Any licensed and recommended influenza vaccine (i.e., any IIV or RIV) that is otherwise appropriate for the recipient’s age and health status may be used.
  • Persons who report having had reactions to egg involving symptoms other than urticaria (hives), such as angioedema, respiratory distress, lightheadedness, or recurrent emesis; or who required epinephrine or another emergency medical intervention, may similarly receive any licensed and recommended influenza vaccine (i.e., any IIV or RIV) that is otherwise appropriate for the recipient’s age and health status. The selected vaccine should be administered in an inpatient or outpatient medical setting (including, but not necessarily limited to, hospitals, clinics, health departments, and physician offices). Vaccine administration should be supervised by a health care provider who is able to recognize and manage severe allergic conditions.
  • A previous severe allergic reaction to influenza vaccine, regardless of the component suspected of being responsible for the reaction, is a contraindication to future receipt of the vaccine.