Phase III stakes are always high. But for Merck & Co. Inc., results of a late-stage test of its SARS-CoV-2 antiviral, molnupiravir, stand to determine not just the fate of a desired emergency use authorization (EUA), but also a $1.2 billion purchase agreement with the U.S. government pending the EUA. The RNA polymerase inhibitor, invented at Emory University and developed with Ridgeback Biotherapeutics LP, is being evaluated in a phase III study for the treatment of non-hospitalized patients with mild to moderate COVID-19. An earlier study found it unlikely to deliver clinical benefit for hospitalized patients.