Question & Answer

In your February 2021 editor’s column “Our Current Views on the First Two FDA-Authorized COVID-19 Vaccines,” you noted that there had been rare cases of a severe allergic reaction known as anaphylaxis reported in recipients of the Pfizer-BioNTech COVID-19 vaccine. Do you have any new information about the risk of allergic reactions in recipients of the COVID-19 vaccines?

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) have been closely monitoring reports of adverse events in recipients of the COVID-19 vaccines that have been submitted to the Vaccine Adverse Event Reporting System (VAERS), which is co-managed by both agencies.[1]

On Jan. 6, the CDC and FDA published data on allergic reactions, including anaphylaxis, after the first dose of the Pfizer-BioNTech COVID-19 vaccine.[2] As of Dec. 23, 2020, approximately 1.9 million people in the U.S. had received the first dose of the vaccine, and 4,393 reports of adverse events post-vaccination had been submitted to VAERS. Among these reports, 175 were identified as possible cases of severe allergic reactions. After further review, 21 cases were determined to be anaphylaxis (a rate of 11 cases per million doses), 86 were judged to be non-anaphylaxis allergic reactions and 61 were considered non-allergic events. Of the 21 anaphylaxis events, 17 occurred in people with a documented history of allergies or allergic reactions, seven of whom had a history of anaphylaxis. The median interval between vaccination and onset of anaphylaxis symptoms was 13 minutes, with a range of two to 150 minutes.

On Jan. 22, the CDC and FDA published data on allergic reactions, including anaphylaxis, after the first dose of the Moderna COVID-19 vaccine, which was codeveloped by the National Institutes of Health.[3] As of Jan. 10, 2021, approximately 4 million people in the U.S. had received the first dose of the vaccine, and 1,266 reports of adverse events post-vaccination had been submitted to VAERS. Among these reports, 108 were identified as possible cases of severe allergic reactions. After further review, 10 cases were determined to be anaphylaxis (a rate of 2.5 cases per million doses), 47 were judged to be non-anaphylaxis allergic reactions and 47 were considered non-allergic events. Of the 10 anaphylaxis events, nine occurred in people with a documented history of allergies or allergic reactions, five of whom had a history of anaphylaxis. The median interval between vaccination and onset of anaphylaxis symptoms was eight minutes, with a range of one to 45 minutes.

In light of this data, our conclusion remains that the benefits of both vaccines outweigh their risks.
 

References

[1] VAERS, Vaccine Adverse Event Reporting System. About VAERS. https://vaers.hhs.gov/about.html. Accessed February 4, 2021.

[2] CDC COVID-19 Response Team; 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;70(2):46-51.

[3] CDC COVID-19 Response Team; 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 January 22;70. Early release https://www.cdc.gov/mmwr/volumes/70/wr/pdfs/mm7004e1-H.pdf. Accessed February 4, 2021.