The emergence of the Omicron and speculation that it could trigger new lockdowns and reduce fuel demand has roiled markets across assets all week.
Earlier in the day, oil prices rose more than $2 per barrel after producer group OPEC+ said it may soon review its policy to increase output if a growing number of pandemic restrictions stifle demand.
Crude oil prices ended with little change on Friday after wiping out previous big gains amid rising coronavirus cases and growing concerns that the new variant Omicron could curb global oil demand.
Brent futures rose 21 cents, or 0.3%, to settle at $69.88 a barrel, while West Texas Intermediate (WTI) crude fell 24 cents, or 0.4%, to $66.26 a barrel.
Both indicators fell for the sixth week in a row for the first time since November 2018, and both remained in technically oversold territory for the sixth day for the first time since September 2020.
The Organization of the Petroleum Exporting Countries, Russia and its allies known as OPEC+ stunned the market on Thursday, adhering to plans to add 400,000 barrels of supply (bpd) in January.
However, OPEC+ left the door open that it would quickly make changes if demand surges as a result of measures to contain the spread of the Omicron coronavirus variant, and said they could meet again before their next meeting on January 4.
Omicron cases were also found in the USA. The World Health Organization has urged countries to vaccinate their people to fight the virus, saying travel restrictions are not the solution.
U.S. employment growth slowed significantly and disappointed in November due to job losses in retailers and local government education.
U.S. oil rig count held steady at April 2020 high. According to Baker Hughes, US drillers did not change the number of oil rigs this week after previously raising it to its highest level since April 2020 for five consecutive weeks.