Given widespread reports of allergic and anaphylactic reactions to the Pfizer and Moderna COVID-19 vaccines, allergists are likely receiving questions from patients, the general public and community partners. As such, the AAAAI COVID-19 Response Task Force recognizes the importance of providing background and framework to assist these inquiries. Given that vaccine distribution in the United States only began in mid-December 2020, this information is expected to change and evolve as the robust and transparent reporting system monitors ongoing reports of adverse events. Therefore, it is not feasible to provide continuous updates addressing each new development, but healthcare professionals should continue to monitor both the CDC reports and AAAAI COVID-19 Response Task Force updates for pertinent information.
Summary of Anaphylaxis Reported to COVID-19 Vaccines
- Adverse reactions, including anaphylaxis, have been widely monitored and updated consistently. Thus far, the data are reassuring and indicate low risk for anaphylaxis. Among the first 22 million doses of COVID-19 vaccine administered in the United States, anaphylaxis has been extremely rare. As of January 18, 2021, and as part of the VAERS data presented to the Advisory Committee on Immunization Practices, the rate of anaphylaxis to the Pfizer vaccine was 5 per million doses and 2.5 per million for Moderna.
- All cases of anaphylaxis were treated effectively and resulted in full recovery. The majority of these reported episodes occurred within 15 minutes of vaccine administration.
- While the majority of the people who experienced anaphylaxis also self-reported a history of allergies, there is no consistent factor in regards to type of allergy, i.e., food, venom, environmental, medication.
- The mechanism of action surrounding reported anaphylactic reactions has not been identified or confirmed. There continues to be speculation regarding potential IgE-mediated reactions to polyethylene glycol (PEG), but this has not been confirmed and prior to the COVID-19 vaccine distribution, reports of hypersensitivity reactions to this ingredient were very rare.
Guidance Prior to the First COVID-19 Vaccine Dose, All Referenced on the CDC Website
- All COVID-19 vaccines should be administered in a facility where each person can be monitored for at least 15 minutes with treatment readily available for anaphylaxis. Anyone with a history of non-anaphylactic reactions to food, oral medication, latex, environmental, or venom allergens can safely receive either the Pfizer or Moderna vaccine in this manner.
- Anyone with a history of anaphylaxis to food, oral medication, latex, environmental, or venom allergies can receive either the Pfizer or Moderna vaccine without any precautions other than a recommended 30-minute observation period.
- Anyone with a history of immediate onset hypersensitivity reactions (urticaria, wheezing, angioedema, anaphylaxis) to any prior vaccine or injected medication can receive either the Pfizer or Moderna vaccine with a recommended 30-minute observation period. Consultation with an allergist to discuss risks/benefits may also be considered.
- Anyone with known and proven IgE mediated reactions to PEG or polysorbate are currently advised to avoid the Pfizer and Moderna vaccines. Given the rarity of allergies to these ingredients, it is unlikely for anyone to have this known allergy, unless specifically evaluated by a board certified allergist and confirmed with prior skin testing.
Guidance Prior to the Second COVID-19 Vaccine Dose
- If a person received the first dose uneventfully, then they can receive the second dose in the same manner.
- If a person experienced delayed onset symptoms, including rash, swelling, lymphadenopathy, fever, fatigue, etc., then they should not be considered at increased risk for anaphylaxis with the second dose. Consultation with an allergist may be beneficial to discuss risks/benefits of receiving the second dose under closer observation, or in the standard manner. Skin testing to vaccine components is not indicated in these situations.
- If a person experienced immediate onset symptoms within the first 4 hours of their first COVID-19 vaccine, then a detailed history and review of medical records (if available from any emergency department evaluation) should be reviewed to determine if symptoms are consistent with an IgE-mediated reaction. Many symptoms may mimic IgE-mediated reactions and would not represent a contraindication to subsequent vaccine administration, including vaso-vagal responses, vocal cord dysfunction, flushing without urticaria, subjective symptoms such as tingling or itching without urticaria, or hypertension.
- If the history is highly suggestive for possible IgE-mediated reaction to the first COVID-19 vaccine dose, then evaluation by an allergist should be considered. Shared decision making regarding risks and benefits of receiving a second dose should be discussed, including options to avoid, receive under physician supervision, or evaluation with skin testing. Given the speculation surrounding potential reactions to PEG or polysorbate, skin testing protocols with non-irritant concentrations have been published for the allergist to consider as part of their evaluation, but are not validated or currently recommended in every situation. Although these vaccines do not contain polysorbate, there are reports of cross-reactivity with PEG and future vaccines do contain polysorbate.
- Skin testing to the vaccine is of unclear utility in evaluating possible allergic reactions to these vaccines. The validity of this approach has not been proven, nor have non-irritant concentrations been determined. Further, from a public health standpoint, the stock of vaccines is limited and (at this time) is likely better used for vaccinations rather than evaluation of potential reactions.
Role of the Allergist in COVID-19 Vaccine Distribution
- Allergists can communicate important concepts surrounding IgE-mediated hypersensitivity reactions, anaphylaxis, delayed onset immunologic reactions, and non-immunologic reactions.
- Allergists can assist patients in understanding risk and benefit, with an emphasis on context and perspective (anaphylaxis to the COVID-19 vaccines is very rare and easily treated, whereas infection may cause risk for severe illness).
- Allergists can help patients and the general public better understand risk, particularly given variable levels of health literacy (i.e., 999,997 out of 1 million people received the Moderna vaccine without having an allergic reaction).
- Allergists can promote shared decision making and help each individual patient identify their values and preferences to help guide decision making.