Study characteristics and risk of bias assessment
The studies were conducted in the USA, Puerto Rico, Brazil, and Argentina and included individuals with mild or moderate laboratory-confirmed SARS-CoV-2 infection. All trial protocols were registered on ClinicalTrials.gov, had a parallel design, and were classified as Phase 2 or Phase 3. Population characteristics, dosage of nitazoxanide, outcomes of interest, and the time of outcomes assessment are detailed in Table 1. Most trials evaluating nitazoxanide as treatment for patients with COVID-19 had a low risk for selection, performance, detection, attrition, and information bias. Two studies were classified as high-risk for reporting bias [16,17] and two studies as high-risk for operational bias [15,16] (eFigure 2; supplementary file).