The trial is designed to evaluate the safety and efficacy of VIR-7831 (also known as GSK4182136) for the treatment of hospitalized adults with COVID-19. VIR-7831 is an anti-SARS-CoV-2 investigational monoclonal antibody that was selected based on its potential to neutralize the coronavirus, kill infected cells, provide a high barrier to resistance, and achieve high concentrations in the lungs, the companies said.

ACTIV-3 will compare 300 participants who have been hospitalized with mild to moderate COVID-19 with fewer than 13 days of symptoms. Participants will receive VIR-7831 or placebo as well as standard care for COVID-19, including the antiviral remdesivir.

If the VIR-7831 treatment arm appears to have a positive benefit/risk profile, the trial will enroll an additional 700 participants, including those who are more severely ill. Participants will be followed for 90 days after enrollment to analyze their response to treatment, with the primary efficacy end point being the participants' sustained recovery for 14 days after release from the hospital.

ACTIV-3 is one of several ongoing trials in the NIH's ACTIV program. It has been designed as a "master protocol" that allows for the simultaneous evaluation of multiple investigational therapeutics as they become available, within the same clinical trial structure across multiple sites.