The ACTIV-3 clinical trial, which is evaluating the safety and efficacy of investigational therapeutics for COVID-19 in hospitalized patients, has closed enrollment in two sub-studies: one examining the investigational monoclonal antibody therapy VIR-7831, and another evaluating the investigational combination monoclonal antibody therapy containing BRII-196 and BRII-198. The sub-studies were halted by the trial sponsor, the National Institute of Allergy and Infectious Diseases, on March 1, following an interim review and recommendation from the independent DSMB.