Risk of bias assessment
Risk of bias was judged according to the Cochrane guidelines for RCTs [7]. The following domains were evaluated: sequence generation and allocation concealment (selection bias), blinding of participants and personnel (performance bias), blinding of outcome assessment (detection bias), incomplete outcome data (attrition bias), selective outcome reporting (reporting bias), sample size calculation, power analysis, and early stopping for futility (operational bias), outcome measurements (information bias), and the authors’ financial or non-financial conflicts of interest that could appear to affect the judgment of research team when designing, conducting, or reporting study. Studies using real-time reverse transcription polymerase chain reaction (RT-PCR) to detect SARS-CoV-2 or, if testing was limited, provided a clinical diagnosis based on COVID-19-related symptoms and epidemiological data were considered as having a low risk of bias.