[COVID-19: Critical appraisal of the evidence]

We present the summary of a critical appraisal document of the available evidence on COVID-19, developed with a clinical practice guide format following GRADE methodology. The document tries to provide answers to a series of structured clinical questions, with an explicit definition of the population, intervention/exposure, comparison and outcome, and a rating of the clinical relevance of the outcome measures. We conducted a systematic review of the literature to answer the questions, grouped into six chapters: epidemiology, clinical practice, diagnosis, treatment, prevention, and vaccination. We assessed the risk of bias of the selected studies with standard instruments (RoB-2, ROBINS-I, QUADAS and Newcastle-Ottawa). We constructed evidence tables and, when necessary and possible, meta-analysis of the of the most relevant outcome measures. We followed the GRADE system to synthesize the evidence, assessing its quality, and, when appropriate, giving recommendations, rated according to the quality of the evidence, the values and preferences, the balance between benefits, risks and costs, equity and feasibility.