Search strategy
Searches for studies were performed in PubMed, Web of Science, Scopus, Embase, Google Scholar (first 100 hits), the website ClinicalTrials.gov, and the preprint server medRxiv from January 1, 2020 to June 24, 2021. The search was limited to studies published in full-text versions, without language restriction. In the ClinicalTrials.gov, only completed studies with results were analyzed. The reference lists of all eligible studies and reviews were scanned to identify additional studies for inclusion.
We used the following structured search strategy for each electronic database: (nitazoxanide) AND (COVID-19 OR “2019-nCoV Infection” OR “Coronavirus Disease-19” OR “2019-nCoV Disease” OR SARS-CoV-2). For Google Scholar, ClinicalTrials.gov and medRxiv, we used the following strategy: (nitazoxanide) AND (COVID-19 OR SARS-CoV-2). To expand the number of eligible studies, specific filters for RCTs were not used.