Dec 16 (Reuters) - AstraZeneca (AZN.L) said on Thursday a lab-study of its COVID-19 antibody cocktail, Evusheld, found that the treatment retained neutralising activity against the Omicron coronavirus variant, showing promise for wider use of the therapy. The study was conducted by independent investigators of the U.S. Food and Drug Administration, the company said, adding that more analyses of Evusheld against Omicron are being conducted by AstraZeneca and third-parties, with data expected "very soon".