LAUSR

AGEP: acute generalized exanthematous pustulosis mRNA: messenger RNA INTRODUCTION COVID-19 caused by SARS-CoV-2 is responsible for the current pandemic. The US Food and Drug Administration recently granted emergency authorization of the Pfizer BioNTech and Moderna messenger RNA (mRNA) vaccines for use against COVID-19. Both vaccines utilize a novel technology, in which mRNA encoding the SARS-CoV-2 spike protein enveloped in lipid nanoparticles penetrates the cell membrane into the cytosol and produces a spike protein for subsequent antigen presentation and immune system activation. Although this vaccine technology is presumed to be safe through clinical trials, the full spectrum of adverse effects of mRNA vaccines has not yet been characterized. Nonetheless, a wide range of cutaneous adverse effects has been described with the use of Pfizer BioNTech and Moderna mRNA vaccines. Local immediate and delayed injection site reactions, urticaria, and morbilliform rashes are the most frequently reported adverse effects. We describe a rare cutaneous development of acute generalized exanthematous pustulosis (AGEP) in a patient following vaccination with the Moderna COVID-19 mRNA vaccine.