INTRODUCTION
An outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, which began in Wuhan, China, has emerged as a primary concern all over the world. The World Health Organization announced the risk assessment of coronavirus disease 2019 (COVID-19) as very high at the global level, and fatal cases are rapidly increasing. By March 24, 2020, more than 9,000 people were infected, and 126 people died, in South Korea. Without specific treatments for the virus, treatment options are being studied in addition to supportive care. Evidence shows that the use of convalescent plasma to treat emerging viral infections, including SARS, Middle East respiratory syndrome (MERS), Ebola virus disease or avian flu, can improve survival rates in patients whose condition worsens even with conventional treatment.12 However, the safety and efficacy of convalescent plasma treatment in COVID-19 have not been known. Here, we report two cases of severe COVID-19 patients presenting acute respiratory distress syndrome (ARDS), who showed a favorable clinical course after the convalescent plasma infusion. This is the first report of the use of convalescent plasma to treat cases of SARS-CoV-2 infection in Korea.