Lack of a placebo control group; Design introduces the possibility of biased investigator determined assessment and unbalanced dosage adjustment; Randomization of sequential envelopes may be biased. The antiviral efficacy of HCQ was not assessed at an earlier stage; Most patients are mild to severe, and the effect of HCQ on disease progression or regression could not be provided. The trial terminated early due to the difficulty to recruit enough patients. Some secondary endpoints could not be analyzed by the cutoff date; Viral RNA specimens are mostly from the upper respiratory tract rather than bronchoalveolar lavage fluid, which may cause false negative results.