On Jun. 16, 2021, Pfizer and The Academic Research Organization (ARO) from the Hospital Israelita Albert Einstein announced that the New England Journal of Medicine had published positive findings from the STOP-COVID study (NCT04469114) evaluating the efficacy and safety of oral Janus kinase (JAK) inhibitor tofacitinib in 289 hospitalized adult patients with COVID-19 pneumonia who were not on ventilation.

The trial demonstrated a lower cumulative incidence of death or respiratory failure through day 28 — the primary outcome of the study.