GlaxoSmithKline /zigman2/quotes/209463850/composite GSK +0.65% /zigman2/quotes/200381158/delayed UK:GSK +1.98% and partner Vir Biotechnology /zigman2/quotes/214486077/composite VIR +9.78% said Tuesday that the U.S. government will buy 600,000 doses of sotrovimab, an investigational monoclonal antibody for early COVID-19 treatment. The extra doses will be delivered in the first quarter of 2022 to the U.S., which has an option to purchase more in the second quarter. The companies now have total binding agreements for 1.7 million doses worldwide. Sotrovimab was granted emergency use authorization by the Food and Drug Administration in May 2021 for treatment of mild to moderate COVID-19 in at-risk adults and children 12 and older. Preclinical data has shown sotrovimab is effective against all COVID-19 variants, including delta and omicron. Shares of Glaxo rose 1% in London and Vir shares climbed 3% in the U.S.