(Adds TIPS auction results, U.S. data, updates prices) By Karen Brettell NEW YORK, Dec 22 (Reuters) - U.S. Treasury yields fell on Tuesday as investors weighed the likelihood of new lockdowns stemming from a more infectious variant of the coronavirus in the United Kingdom against the impact of U.S. fiscal stimulus. Benchmark 10-year yields fell to 1-1/2 week lows early on Monday as countries shut off travel ties with the UK. The yields have since fluctuated as investors focus on whether the new variant will be resistant to vaccines. BioNTech is testing the effectiveness of the COVID-19 vaccine it developed with Pfizer Inc against the mutation as it prepares to send 12.5 million doses to European Union countries by the end of year. "The markets will continue to assess the threat from the new strain of virus and the more stringent lockdowns," analysts at Action Economics said in a report on Tuesday. At the same time, the stimulus is "helping revive investor sentiment," they added. The U.S. Congress on Monday approved an $892 billion coronavirus aid package after months of inaction. Data on Tuesday showed that U.S. consumer confidence dropped for a second straight month in December as a deterioration in the labor market amid renewed business restrictions to slow the pandemic offset the rolling out of a vaccine for COVID-19. U.S. 10-year yields fell two basis points on the day to 0.918% after falling as low as 0.882% on Monday. The yield curve between two-year and 10-year notes flattened one basis point to 80 basis points, holding just below an almost three-year high of 83 basis points reached on Friday. Longer-dated Treasury yields have risen and the yield curve has steepened on expectations that more fiscal spending and ultra loose Federal Reserve policy will spur higher inflation. Demand was solid for the Treasury Department"s $15 billion auction of five-year Treasury-Inflation-Protected-Securities (TIPS) on Tuesday. The notes sold at a high yield of minus 1.575% and had a bid-to-cover ratio of 2.86 times. Breakeven rates on the five-year TIPS, which measure expected annual inflation, rose to 1.91% on Tuesday, from a low of 1.88% on Monday. Market liquidity is low and expected to decline further with many traders out before Friday"s Christmas holiday. The bond market will close early at 2 p.m. EST on Thursday and be closed on Friday for the Christmas Day. December 22 Tuesday 3:03PM New York / 2003 GMT Price Current Net Yield % Change (bps) Three-month bills 0.0875 0.0887 -0.002 Six-month bills 0.09 0.0913 -0.008 Two-year note 100-3/256 0.1189 -0.004 Three-year note 99-222/256 0.1697 -0.010 Five-year note 100-14/256 0.3638 -0.017 Seven-year note 99-236/256 0.6365 -0.025 10-year note 99-152/256 0.918 -0.023 20-year bond 98-188/256 1.4484 -0.032 30-year bond 99-84/256 1.6536 -0.030 DOLLAR SWAP SPREADS Last (bps) Net Change (bps) U.S. 2-year dollar swap 8.25 0.00 spread U.S. 3-year dollar swap 7.50 0.50 spread U.S. 5-year dollar swap 7.00 0.50 spread U.S. 10-year dollar swap 0.25 0.25 spread U.S. 30-year dollar swap -26.50 0.75 spread (Reporting by Karen Brettell; Editing by Kirsten Donovan and Richard Chang)