Jan 6 (Reuters) - GlaxoSmithKline PLC (GSK.L) said on Thursday it has signed agreements with the Canadian government to supply 20,000 more doses of its COVID-19 drug, as the country battles a surge in infections driven by the Omicron variant. The new purchase agreement follows October"s initial deal to supply 10,000 doses of the drug, sotrovimab, which included an option for Canada to buy more. "In light of emerging variants, and in particular Omicron, I am reassured by the news that the Government of Canada has procured additional doses of sotrovimab," the company said, citing Zain Chagla, associate professor of medicine at McMaster University in Ontario. Sotrovimab is a COVID-19 monoclonal antibody developed by the British pharmaceutical giant with U.S.-based Vir Biotechnology (VIR.O). It was authorized by Health Canada in July for people aged 12 years or older. Besides Canada, sotrovimab is also authorized in regions including the United States, Japan and the European Union. Apart from monoclonal antibodies, Canada has also signed deals to buy 500,000 courses of Merck"s (MRK.N) antiviral COVID-19 pills and a million doses of Pfizer"s (PFE.N) oral COVID-19 antiviral pills. read more