Dec 23 (Reuters) - GSK (GSK.L) and Vir Biotechnology"s (VIR.O) antibody-based COVID-19 drug is being studied as a possible treatment for hospitalised patients in a large British study looking into coronavirus therapies, researchers said on Thursday. The RECOVERY trial will test sotrovimab as the Omicron variant spreads, its website said, with an "urgent need to evaluate alternative therapies." The new strain, first identified in southern Africa and Hong Kong, has worried researchers as the large number of mutations it has will help the virus spread faster and evade the protection offered by shots and therapies currently in use. Laboratory studies have shown that sotrovimab is effective against all mutations of Omicron, GSK said this month, citing new data from early-stage studies. "We hope to begin testing sotrovimab next week," said Peter Horby, joint chief investigator of RECOVERY and an Oxford University professor. "We lack good antivirals, and hope that we will be able to add other antiviral treatments to the trial". Treatments that have been or being tested in the RECOVERY trial include arthritis drug tocilizumab, steroid dexamethasone, common antibiotic azithromycin, painkiller aspirin, and Regeneron"s (REGN.O) antibody cocktail. Britain"s drug regulator earlier this month approved the GSK-Vir treatment, branded Xevudy, for people with mild-to-moderate COVID-19 who are at high risk of developing severe disease.