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.