Convalescent plasma was administered after 22 days from the onset of symptoms in Case 1, and 7 days in Case 2, respectively. Because these are not in the early phase of the disease, it is difficult to determine clearly that the decrease in the viral load shown in both cases is due to convalescent plasma or natural pathology of COVID-19. Other studies about viral kinetics of COVID-19 show naturally reducing viral titers after 7–10 days from onset in most patients.1617 However, Liu and colleagues reported that severe patients requiring intensive care unit admission due to COVID-19 had high viral load for a longer period than in mild patients.16 Both our cases presented severe ARDS and the viral loads were in increasing trend at the time of plasma infusion regardless of the date of onset.