“COVID arm”: A reaction to the Moderna vaccine

The Moderna mRNA-1273 vaccine was authorized by the Food and Drug Administration for emergency use during the ongoing COVID-19 pandemic in December 2020.1 Out of 15,185 participants in the phase III Coronavirus Efficacy (COVE) trials who received at least one dose of the Moderna vaccine, 228 (1.5%) reported hypersensitivity adverse events, including injection site rash and urticaria.2 Although we have seen an eruptive, morbilliform rash that manifests 48 hours postvaccination that is similar to a drug rash (Fig 1), we report 4 cases of “COVID arm”: a localized erythematous rash surrounding the injection site that manifests days after the first dose of the Moderna COVID-19 vaccine.