LONDON—Oil rose above $78 a barrel on Monday, supported by tight supply and hopes of a further demand recovery in 2022. OPEC and its allies, or OPEC+, are expected on Tuesday to agree to the output hike. The Omicron coronavirus variant has brought record case counts and dampened New Year festivities worldwide, with more than 4,000 flights canceled on Sunday. Brent crude was up 39 cents, or 0.5 percent, to $78.17 a barrel at 1444 GMT, having earlier risen as high as $79.05. U.S. West Texas Intermediate (WTI) crude slipped 25 cents or 0.3 percent, to $74.96. “Infection rates are on the rise globally, restrictions are being introduced in several countries, the air travel sector, amongst others, is suffering, yet investors’ optimism is tangible,” said Tamas Varga of oil broker PVM. “In a nutshell, 2021 demonstrated that the war against the coronavirus is a winnable one although the path to …