LONDON—Oil prices slipped below $80 a barrel on Wednesday after OPEC+ producers stuck to an agreed output target rise for February and investors assessed the impact of a spike in COVID-19 cases caused by the Omicron variant. Brent crude futures were down 18 cents, or 0.23 percent, to $79.82 a barrel by 0945 GMT, while U.S. West Texas Intermediate (WTI) crude futures declined 23 cents, or 0.3 percent, to $76.76. OPEC+ producers, which include members of the Organization of the Petroleum Exporting Countries along with Russia and others, on Tuesday, agreed to add another 400,000 barrels per day of supply in February, as they have done each month since August. While OPEC+ raised its output target, it will likely struggle to reach it, as members including Nigeria, Angola, and Libya face difficulties ramping up production, Barclays analysts said in a note. “OPEC+ has adopted the path of least (political) resistance, …