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 (2016-2017). 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.
Recommendations for flu vaccination of persons with egg allergy have not changed since the 2016-2017 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.
What is considered an egg allergy? What are the signs and symptoms of an egg allergic reaction?
Egg allergy can be confirmed by a consistent medical history of adverse reactions to eggs and egg-containing foods, plus skin and/or blood testing for immunoglobulin E antibodies to egg proteins. Persons who are able to eat lightly cooked egg (e.g., scrambled egg) without reaction are unlikely to be allergic. Egg-allergic persons might tolerate egg in baked products (e.g., bread or cake). Therefore, tolerance to egg-containing foods does not exclude the possibility of egg allergy. Egg allergies can range in severity.
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 be allergic 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 by a health care provider who can recognize and respond to a severe allergic response.
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.
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. Cell-based flu vaccine (Flucelvax) likely has a much smaller amount of egg protein since the original vaccine virus is grown in eggs, but mass production of that vaccine does not occur in eggs. Recombinant vaccine (Flublok) is the only vaccine currently available that is 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.
Thimerosal in Flu Vaccine
What is thimerosal?
Thimerosal is an ethyl mercury-based preservative used in vials that contain more than one dose of a vaccine (multi-dose vials) to prevent germs, bacteria and/or fungi from contaminating the vaccine.
Do flu vaccines contain thimerosal?
Flu vaccines in multi-dose vials contain thimerosal to safeguard against contamination of the vial. Most single-dose vials and pre-filled syringes of flu shot and the nasal spray flu vaccine do not contain a preservative because they are intended to be used once.
A list of available flu vaccines and their thimerosal content is available.
Why are preservatives sometimes used in vaccines?
Preservatives are used to protect vaccines packaged in multi-dose vials. Each time a vaccine dose is drawn from a multi-dose vial, bacteria or fungi can enter the vial. Receiving a vaccine contaminated with bacteria or fungi can be dangerous. Preservatives are needed to prevent contamination of multi-dose vials each time individual doses are drawn.
Thimerosal use in vaccines and other medical products has a record of being very safe. Data from many studies show no evidence of harm caused by the low doses of thimerosal in vaccines.
Where can I learn more about thimerosal?
Please visit CDC’s webpage Thimerosal in Vaccines for more information on thimerosal, including Frequently Asked Questions about Thimerosal.
Misconceptions about Flu Vaccines
Can a flu vaccine give you the flu?
No, flu vaccines cannot cause flu illness. Flu vaccines given with a needle (i.e., flu shots) are currently made in two ways: the vaccine is made either with a) flu viruses that have been ‘inactivated’ (killed) and that therefore are not infectious, or b) using only a single gene from a flu virus (as opposed to the full virus) in order to produce an immune response without causing infection. This is the case for recombinant influenza vaccines.
Are any of the available flu vaccines recommended over the others?
For the 2019-2020 flu season, the Advisory Committee on Immunization Practices recommends annual influenza (flu) vaccination for everyone 6 months and older with any licensed, influenza vaccine that is appropriate for the recipient’s age and health status, including inactivated influenza vaccine (IIV), recombinant influenza vaccine (RIV), or live attenuated nasal spray influenza vaccine (LAIV4) with no preference expressed for any one vaccine over another.
There are many vaccine options to choose from, but the most important thing is for all people 6 months and older to get a flu vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.
Is it better to get the flu than the flu vaccine?
No. Flu can be a serious disease, particularly among young children, older adults, and people with certain chronic health conditions, such as asthma, heart disease or diabetes. Any flu infection can carry a risk of serious complications, hospitalization or death, even among otherwise healthy children and adults. Therefore, getting vaccinated is a safer choice than risking illness to obtain immune protection.
Do I really need a flu vaccine every year?
Yes. CDC recommends a yearly flu vaccine for just about everyone 6 months and older, even when the viruses the vaccine protects against have not changed from the previous season. The reason for this is that a person’s immune protection from vaccination declines over time, so an annual vaccination is needed to get the “optimal” or best protection against the flu.
Why do some people not feel well after getting the seasonal flu vaccine?
Some people report having mild reactions to flu vaccination. The most common side effects from flu shots are soreness, redness, tenderness or swelling where the shot was given. Low-grade fever, headache and muscle aches also may occur. If these reactions occur, they usually begin soon after the shot and last 1-2 days. In randomized, blinded studies, where some people get inactivated flu shots and others get salt-water shots, the only differences in symptoms was increased soreness in the arm and redness at the injection site among people who got the flu shot. There were no differences in terms of body aches, fever, cough, runny nose or sore throat.
Side effects from the nasal spray flu vaccine may include: runny nose, wheezing, headache, vomiting, muscle aches, fever, sore throat and cough. If these problems occur, they usually begin soon after vaccination and are mild and short-lived. The most common reactions people have to flu vaccines are considerably less severe than the symptoms caused by actual flu illness.
What about serious reactions to flu vaccine?
Serious allergic reactions to flu vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the vaccination. While these reactions can be life-threatening, effective treatments are available.