January 28, 2021
Allergic Reactions to the Pfizer-BioNTech and Moderna COVID-19 Vaccines: Early Reports
Stephen G. Baum, MD reviewing CDC COVID-19 Response Team and Food and Drug Administration MMWR Morb Mortal Wkly Rep 2021 Jan 15 CDC COVID-19 Response Team and Food and Drug Administration MMWR Morb Mortal Wkly Rep 2021 Jan 22
The CDC's reports in late December 2020 and January 2021 indicated rates of
11.1 and 2.5 anaphylaxis cases per million vaccine doses of the Pfizer-BioNTech and Moderna vaccines, respectively, with no fatalities.An initial CDC report detailed adverse reactions (including anaphylaxis) during the first 10 days of administration of the Pfizer-BioNTech COVID-19 vaccine. During that period (December 14–23, 2020), 1,893,360 first doses of vaccine (encompassing multiple lots) were given and 4393 adverse reactions (0.2%) were reported. Twenty-one of these cases were subsequently defined as anaphylaxis (median age, 40; 90% women), for an incidence of 11.1 per million vaccinations. Median onset of anaphylaxis was 13 minutes (range, 2–150 minutes), with 71% of reactions occurring within 15 minutes (the recommended observation period), 14% within 15–30 minutes, and an additional 14% after 30 minutes. Epinephrine (primarily intramuscular) was administered and no deaths were reported. Eighty-one percent of cases had a documented history of allergies and 33% had experienced anaphylaxis before. Other reactions included pruritis, scratchy throat, mild respiratory symptoms, and rash.
For the Moderna vaccine (released several weeks later), assessment of allergic reactions after administration of 4,041,396 first doses revealed 10 cases meeting criteria for anaphylaxis, yielding a rate of 2.5 such incidents per million vaccinations. Of the patients experiencing this severe reaction, 9 had a previous history of allergies (5 involving anaphylaxis). Female recipients predominated and multiple lots were represented. Nonanaphylactic allergic reactions were similar to those seen with the Pfizer-BioNTech vaccine. Most anaphylaxis occurred within 15 minutes, but one episode occurred at 30 minutes. No deaths occurred.
COMMENT
Although life-threatening anaphylaxis is rare, awareness of its possibility (and availability of epinephrine) is critical, especially as vaccination is extended to nonhospital sites. Because some of these anaphylactic reactions occurred beyond 15 minutes, observing vaccine recipients for at least 30 minutes is judicious.
EDITOR DISCLOSURES AT TIME OF PUBLICATION
Disclosures for Stephen G. Baum, MD at time of publication
Consultant/Advisory Board Clinical Infectious Diseases
Equity Select Medical Holdings Corp. (no annual income is derived from this equity holding)
Editorial Boards Medical Letter
CITATION(S):
CDC COVID-19 Response Team and Food and Drug Administration Allergic reactions including anaphylaxis after receipt of the first dose of Pfizer-BioNTech COVID-19 vaccine — United States, December 14–23, 2020. MMWR Morb Mortal Wkly Rep 2021 Jan 15; 70:46. (Δεν είναι ορατοί οι σύνδεσμοι (links).
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CDC COVID-19 Response Team and Food and Drug Administration Allergic reactions including anaphylaxis after receipt of the first dose of Moderna COVID-19 vaccine — United States, December 21, 2020–January 10, 2021. MMWR Morb Mortal Wkly Rep 2021 Jan 22; [e-pub]. (Δεν είναι ορατοί οι σύνδεσμοι (links).
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