Merck MRK, +0.81% and privately held Ridgeback Biotherapeutics said Wednesday the Japanese government has agreed to purchase $1.6 million courses of their COVID-19 antiviral molnupiravir, once it receives an authorization or approval. Merck and Ridgeback have applied for authorization of the treatment from the U.S. Food and Drug Administration, Japan's Pharmaceuticals and Medical Devices Agency and the European Medicines Agency. Molnupiravir is already authorized in the UK for the treatment of mild-to-moderate COVID-19 in adults who have tested positive for the illness and who have at least one risk factor for developing severe illness. The companies have said data from a clinical trial showed that the drug can reduce the risk of getting hospitalized or dying from a COVID-19 infection by 50%. The drug is expected to be a game changer in the pandemic as it can be administered easily from home in capsule form, while existing treatments have to be administered by intravenous or subcutaneous infusion or are reserved for the sickest patients in the hospital. Merck shares were slightly lower premarket but are up 6% in the year to date, while the S&P 500 SPX, -0.10% has gained 25%.