Dec 21 (Reuters) - U.S. stocks opened lower on Monday as a new strain of the coronavirus in Britain raised fears of further economic disruptions. The Dow Jones Industrial Average fell 20.05 points, or 0.07%, at the open to 30,159.00. The S&P 500 opened lower by 25.13 points, or 0.68%, at 3,684.28. The Nasdaq Composite dropped 159.49 points, or 1.25%, to 12,596.14 at the opening bell. (Reporting by Ambar Warrick in Bengaluru; Editing by Anil D’Silva)