This multi-center, randomized, double-blind, placebo-controlled trial evaluated the effectiveness of tofacitinib – a selective inhibitor of Janus kinase – in COVID-19 patients who were hospitalized, had pneumonia, and were not on ventilation. Patients were given tofacitinib for 14 days or until hospital discharge, whichever was earlier, and they were followed for up to 28 days. The trial enrolled 289 patients across 15 sites in Brazil. The primary endpoint of death or respiratory failure occurred in 18.1% of treated patients and 29.0% of control patients (risk ratio 0.63 [95% CI 0.41, 0.97]). Using the eight-level National Institute of Allergy and Infectious Diseases ordinal scale of disease severity, the proportional odds of patients receiving tofacitinib having a score lower than those receiving placebo was 0.60 [95% CI 0.36, 1.00] at day 14 and 0.54 [95% CI 0.27, 1.06] at day 28. Overall, the results suggest that tofacitinib is superior to placebo in reducing the risk of death or respiratory failure.