Dec 1 (Reuters) - Pfizer Inc (PFE.N) said on Wednesday it had started the real-time submission of its application seeking Health Canada"s approval of its oral COVID-19 antiviral drug candidate. The pill, PF-07321332, is designed to block a key enzyme needed for the coronavirus to multiply.The move comes after the Canadian government announced on Tuesday that it was in advanced talks with Pfizer and Merck & Co Inc (MRK.N) regarding a purchase agreement for their COVID-19 antiviral drugs, as the country attempts to control the spread of the Omicron coronavirus variant. The country has identified seven people with the new variant as of Nov. 30. read moreThe drugmaker last month submitted its application seeking U.S. authorization of the experimental pill, which was shown to cut the chance of hospitalization or death for adults at risk of severe disease by 89% in a clinical trial. read more