Updated Jan. 8, 2021
Reactions to vaccines, in general, are rare with the incidence of anaphylaxis estimated at 1.31 in 1 million doses given. With the FDA emergency use authorization of the Pfizer-BioNTech COVID-19 vaccine on Dec. 11, 2020, and the Moderna vaccine on Dec. 18, 2020, the ACAAI COVID-19 Vaccine Task Force recommends the following guidance for physicians and other providers related to risk of an allergic reaction on vaccination.
These recommendations are based on best knowledge to date but could change at any time, pending new information and further guidance from the FDA or CDC.
- All subjects should be screened to determine possible risk of an allergic reaction to the mRNA COVID-19 vaccines.
♦ Do you have a history of a severe allergic reaction to an injectable medication (intravenous, intramuscular, or subcutaneous)?
♦ Do you have a history of a severe allergic reaction to a prior vaccine?
♦ Do you have a history of a severe allergic reaction to polyethylene glycol (PEG), a polysorbate or polyoxyl 35 castor oil (e.g. paclitaxel) containing injectable or vaccine?Modified from Banerji A et al. The Journal of Allergy and Clinical Immunology: In Practice (2021). If yes to any of these answers, the subject should be referred to a board-certified allergist/immunologist for further evaluation prior to COVID-19 vaccination.
- The mRNA COVID-19 vaccines should be administered in a health care setting where anaphylaxis can be treated. All individuals must be observed for at least 15-30 minutes after injection to monitor for any adverse reaction. All anaphylactic reactions should be managed immediately with epinephrine as the first line treatment. Where possible within 90 minutes of an allergic reaction, blood should be collected from the patient to measure serum tryptase (a mast cell marker) and SC5b-9 (the terminal complement complex), which may be elevated in anaphylaxis. According to the CDC, the following laboratories can do the above tests: Tryptase – ARUP Laboratories, Labcorp, and Quest Diagnostics; SC5b-9- Quest Diagnostics and Clinical Laboratory Clinic at National Jewish Hospital.
- The mRNA COVID-19 vaccines should not be administered to individuals with a known history of a severe allergic reaction to any component of the vaccine. Although the specific vaccine component causing the anaphylaxis has not been identified, polyethylene glycol (PEG) is one of the ingredients and has been known to cause anaphylaxis. Since polysorbate, an excipient found in medications and foods, can cross-react with PEG, patients with allergic reactions to polysorbate should not be immunized with the mRNA vaccines.
- The CDC has issued guidance on COVID-19 vaccines and severe allergic reactions and immediate allergic reactions. According to the CDC, if you have had a severe or an immediate allergic reaction of any severity within four hours after getting the first shot, you should not get the second shot. Additionally, patients who experience a severe or an immediate allergic reaction of any severity, or who have questions related to risk of an allergic reaction, may be referred to a local board-certified allergist/immunologist to provide more care or advice.
- The ACAAI does not endorse any testing protocol for PEG, polysorbate, or the mRNA COVID vaccines at this time because we don’t yet know the safety and predictive values of these tests. However, there are some allergic testing protocols for the above that have been published in the medical literature and linked here:
♦ Banerji A, Wickner PG, Saff R, Stone CA Jr, Robinson LB, Long AA, Wolfson AR, Williams P, Khan DA, Phillips E, Blumenthal KG, mRNA Vaccines to Prevent COVID-19 Disease and Reported Allergic Reactions: Current Evidence and Approach, The Journal of Allergy and Clinical Immunology: In Practice (2021).
♦ Stone CA, Liu Y, et al. Immediate Hypersensitivity to Polyethylene Glycols and Polysorbates: More Common Than We Have Recognized. J Allergy Clin Immunol Pract. 2019; 7(5): 1533–1540.)
- Data regarding risk in individuals with a history of allergic reactions related to mast cell activation syndrome/idiopathic anaphylaxis is very limited and evolving. A decision to receive either of the mRNA COVID-19 vaccines should be undertaken by patients with their physician or other provider administering the vaccine using their professional judgment balancing the benefits and risks associated with taking the vaccine.
- People with common allergies to medications, foods, inhalants, insects and latex are no more likely than the general public to have an allergic reaction to the mRNA COVID-19 vaccines. Those patients should be informed of the benefits of the vaccine versus its risks.
- The mRNA COVID-19 vaccines are not live vaccines and can be administered to immunocompromised patients. Physicians and other providers should inform such immunocompromised patients of the possibility of a diminished immune response to the vaccines.
Banerji A, Wickner PG, Saff R, Stone CA Jr, Robinson LB, Long AA, Wolfson AR, Williams P, Khan DA, Phillips E, Blumenthal KG, mRNA Vaccines to Prevent COVID-19 Disease and Reported Allergic Reactions: Current Evidence and Approach, The Journal of Allergy and Clinical Immunology: In Practice (2021)
McNeil MM, Weintraub ES, Duffy J, et al. Risk of anaphylaxis after vaccination in children and adults. J Allergy Clin Immunol. 2016; 137(3):868-878.
Dreskin et al. International Consensus (ICON): allergic reactions to vaccines. World Allergy Organization Journal 2016; 9:32.
Wylon, K., Dölle, S. & Worm, M. Polyethylene glycol as a cause of anaphylaxis. J Allergy Asthma Clin Immunol. 12, 67 (2016).
Stone CA, Liu Y, et al. Immediate Hypersensitivity to Polyethylene Glycols and Polysorbates: More Common Than We Have Recognized. J Allergy Clin Immunol Pract. 2019; 7(5): 1533–1540.