Almost immediately after the first mRNA-based COVID-19 vaccines were authorized for emergency use and administered to individuals outside of clinical trials, reports of anaphylaxis—a life-threatening whole-body allergic reaction—raised widespread concerns among experts and the public. Now, real world data on vaccinations among employees at Mass General Brigham provide reassurances of the rarity of such serious reactions, and the ability to recover from them. The findings are published in the Journal of the American Medical Association.
