Early safety monitoring of the Pfizer-BioNTech COVID-19 vaccine has detected 21 cases of anaphylaxis after reported administration of 1,893,360 first doses of Pfizer-BioNTech COVID-19 vaccine (11.1 cases per million vaccine doses administered) as well as cases of less severe nonanaphylaxis allergic reactions, based on U.S. data for December 14–23, 2020.

Most (86%) anaphylaxis cases had symptom onset within 30 minutes of vaccination, and most persons with anaphylaxis (81%) had a history of allergies or allergic reactions, including some with previous anaphylaxis events; up to 30% of persons in the general population might have some type of allergy or history of allergic reactions.

Most (90%) reported anaphylaxis cases after receipt of Pfizer-BioNTech COVID-19 vaccine occurred in women, although 64% of the vaccine doses administered with sex of recipient recorded were given in women.

Whereas a female predominance has been previously observed in a review of immediate hypersensitivity reports to VAERS after influenza A(H1N1) vaccine (8), the current finding could be impacted by the observation that more women than men had received a first dose of Pfizer-BioNTech COVID-19 vaccine during the analytic period.

Anaphylaxis is potentially life-threatening and requires immediate treatment.

Based on early safety monitoring, anaphylaxis after the Pfizer-BioNTech COVID-19 vaccine appears to be a rare event; however, comparisons of anaphylaxis risk with that associated with non-COVID-19 vaccines are constrained at this time by the limited data available this early in the COVID-19 vaccination program.

CDC and FDA will continue enhanced monitoring for anaphylaxis among recipients of COVID-19 vaccines.

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