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 CDC’s Morbidity and Mortality Weekly Report. The researchers found reports of 1,266 (0.03%) 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 the 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 (2.5 anaphylaxis cases per million 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.
