ration of pneumonia, improving lung imaging, promoting viral conversion and shortening the course of disease. Serious adverse effects were not observed in these patients [48]. However, this report did not provide any details about the study design and patient data, thus it is difficult to evaluate the validity. Recently, a parallel, double-blind, randomized, phase IIB clinical trial was performed in Brazil [49]. In this study, 81 severe COVID-19 patients were randomly divided into