On Mar. 5, 2021, Merck and Ridgeback Biotherapeutics, announced preliminary results from Ridgebackﾒs Phase 2a randomized, double-blind, placebo-controlled trial to evaluate the safety, tolerability, and efficacy to eliminate SARS-CoV-2 viral RNA of molnupiravir (EIDD-2801/MK-4482), an investigational oral antiviral agent.

The companies reported findings on one secondary objective from the Phase 2a study, showing a reduction in time (days) to negativity of infectious virus isolation in nasopharyngeal swabs from participants with symptomatic SARS-CoV-2 infection, as determined by isolation in Vero cell line culture.