Multisystem Inflammatory Syndrome in an Adult Who Received Casirivimab-Imdevimab (REGEN-COV).

Multisystem inflammatory syndrome in adults (MIS-A) is a systemic inflammatory syndrome that presents with a heterogeneous collection of signs and symptoms in adults. Here we present a case of a 38-year-old male who met the case definition of the MIS-A four weeks after a mild, symptomatic case of coronavirus disease 2019 (COVID-19) despite receiving casirivimab-imdevimab (REGEN-COV). Given the presence of signs and symptoms consistent with MIS-A, the patient was started on intravenous immune globulin (IVIG) and IV methylprednisolone. He promptly demonstrated clinical improvement over the next several days.