MONDAY, Jan. 25, 2021 (HealthDay News) -- The rate of anaphylaxis is 2.5 cases per million Moderna COVID-19 vaccine doses administered as of Jan. 10, 2021, according to research published in the Jan. 22 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.
Researchers from the CDC COVID-19 Response Team describe allergic reactions, including anaphylaxis, after receipt of the first dose of the Moderna COVID-19 vaccine in the United States as of Jan. 10, 2021.
The researchers found reports of 1,266 (0.03 percent) adverse events after receipt of the Moderna COVID-19 vaccine were submitted to the Vaccine Adverse Event Reporting System as of Jan. 10, 2021, when 4,041,396 first doses of Moderna COVID-19 vaccine had been administered in the United States. One hundred eight of these case reports were identified for further review as possible severe allergic reaction. Ten of these case reports were determined to be anaphylaxis (rate, 2.5 anaphylaxis cases per million Moderna COVID-19 vaccine doses administered). Nine occurred in individuals with a documented history of allergies or allergic reactions; five of these individuals had anaphylaxis history. All eight of the cases with follow-up information available had recovered and been discharged home. Of the remaining case reports, 47 were assessed to be nonanaphylaxis allergic reactions and 47 were nonallergic adverse events. For four case reports, insufficient data were available to assess the likelihood of anaphylaxis.
"Based on this early monitoring, anaphylaxis after receipt of Moderna COVID-19 vaccine appears to be a rare event," the authors write.