A of January 10, 2021, 10 cases of anaphylaxis had been reported after the administration of Moderna’s COVID-10 vaccine – or a rate of 2.5 anaphylaxis cases per million doses, the Centers for Disease Control and Prevention (CDC) reported in its Morbidity and Mortality Weekly Report (MMWR).
A total of 4,041,396 first doses of Moderna COVID-19 vaccine had been administered in the United States as of January 10, 2021 and reports of 1,266 (0.03 percent) adverse events after receipt of Moderna COVID-19 vaccine were submitted to the Vaccine Adverse Event Reporting System (VAERS). Among these, 108 case reports were identified for further review as possible cases of severe allergic reaction, including anaphylaxis, which is a life-threatening allergic reaction. Ten cases were determined to be anaphylaxis, including nine in persons with a documented history of allergies or allergic reactions, five of whom had a previous history of anaphylaxis.
The median interval from vaccine receipt to symptom onset was 7.5 minutes. Among eight persons with follow-up information available, all had recovered or been discharged home.
A previous analysis of the Pfizer-BioNTech COVID-19 vaccine, also an mRNA vaccine, estimated an initial rate of anaphylaxis of 11.1 cases per million doses administered.
