If it is not possible that it could've played a role, then why are health care staff taught to ask if patients are allergic to eggs before giving the vax?
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or which vaccines is an egg allergy a contraindication?
1) Yellow fever is contraindicated for people who have a history of a severe (anaphylactic) allergy to eggs.
2) People who have experienced a serious systemic or anaphylactic reaction (e.g., hives, swelling of the lips or tongue, acute respiratory distress, or collapse) after eating eggs should consult a specialist for appropriate evaluation to help determine if influenza vaccine should be administered. A previous severe allergic reaction to influenza vaccine, regardless of the component suspected to be responsible for the reaction, is a contraindication to future receipt of the vaccine.
People who have documented immunoglobulin E (IgE)-mediated allergy to eggs, including those who have had occupational asthma or other allergic responses to egg protein, might also be at increased risk for allergic reactions to influenza vaccine. Protocols have been published for safely administering influenza vaccine to people with egg allergies. Some people who report allergy to egg might not be egg allergic. If a person can eat lightly cooked eggs (e.g., scrambled eggs), they are unlikely to have an egg allergy. However, people who can tolerate egg in baked products (e.g., cake) might still have an egg allergy. If the person develops hives only after ingesting eggs, CDC recommends (1) they receive IIV (not LAIV), (2) the vaccine be administered by a healthcare provider familiar with the potential manifestations of egg allergy, and (3) the vaccine recipient be observed for at least 30 minutes after receipt of the vaccine for signs of a reaction.
If someone has a severe allergy to eggs with symptoms suggestive of anaphylaxis and is age 18 years or older, the provider can consider using Flublok, a recombinant influenza vaccine that is egg-free. Unlike current production methods for other available seasonal influenza vaccines, production of Flublok does not use the whole influenza virus or chicken eggs in its manufacturing process. If Flublok is not available or the patient is not age-eligible, then the patient should be referred to a provider experienced in managing allergy. Additional information about Flublok is available at www.cdc.gov/flu/protect/vaccine/qa_flublok-vaccine.htm.
For more details about giving influenza vaccine to people with a history of egg allergy, see the current ACIP recommendations on influenza vaccine, available at www.cdc.gov/vaccines/hcp/acip-recs/index.html. You may also find the IAC handout "Influenza Vaccination of People with a History of Egg Allergy" helpful (see www.immunize.org/catg.d/p3094.pdf).