Update on Severe Allergic or Anaphylactic Reactions to Initial Dose of Pfizer COVID-19 Vaccine

A report from two CDC scientists was published online today in JAMA Insights which describes in detail 21 cases of anaphylaxis that were reported to the US Vaccine Adverse Events Reporting System between December 14-23, 2020.

This corresponds to a very low rate of 11.1 cases of anaphylaxis per million doses administered.

17 of these cases were treated in an ER and sent home and no deaths were reported.

Median interval from vaccine receipt to symptom onset was 13 minutes (range, 2-150 minutes); 15 patients (71%) had onset within 15 minutes; 18 (86%) had onset within 30 minutes. The most common symptoms and signs were urticaria, angioedema, rash, and a sense of throat closure. Seventeen (81%) of 21 patients with anaphylaxis had a documented history of allergies or allergic reactions, including to drugs or medical products, foods, and insect stings

Only one-third of these patients had an episode of anaphylaxis in the past, (one after rabies vaccine and one after influenza A(H1N1) vaccine.)

The CDC guidance on management of anaphylaxis was reiterated:

Specifically, vaccination locations should (1) ensure that necessary supplies are available to manage anaphylaxis, especially sufficient quantities of epinephrine in prefilled syringes or autoinjectors; (2) screen potential vaccine recipients to identify persons with contraindications and precautions; (3) implement recommended postvaccination observation periods, either 15 or 30 minutes depending on each patient’s previous history of allergic reactions; (4) ensure that physicians and other health care professionals can recognize signs and symptoms of anaphylaxis early; and (5) immediately treat suspected anaphylaxis with intramuscular epinephrine (because of the acute, life-threatening nature of anaphylaxis, there are no contraindications to epinephrine administration).

I continue to urge all my patients to get vaccinated as soon as possible. Benefits far outweigh the risk.

Skeptically Yours,

-ACP

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