Abstract
Numerous adverse reactions to the COVID-19 vaccine have been reported, but delayed injection-site reactions at the injection site (COVID arm) are not well recognized. Such reactions are characterized by pruritic erythema, induration, and tenderness that develop approximately 1 week after the first dose of COVID-19 vaccination, and they usually resolve in 4 to 5 days. Most patients develop similar or mild reactions after the second vaccine dose, and these reactions may occur sooner than the first-dose symptoms. In contrast to immediate hypersensitivity reactions, such as anaphylaxis and urticaria, these delayed reactions are not a contraindication to subsequent vaccination. Considering the promotion of mass vaccination, the number of patients with delayed injection-site reactions will increase. We should be aware of the characteristics of these reactions. Here, I report two cases of delayed injection-site reactions caused by COVID-19 vaccine.
