West Texas Intermediate crude for January delivery dropped $10.24, or 13.1%, to close at $68.15 a barrel on the New York Mercantile Exchange, the biggest one-day drop for a front-month contract since April 20, 2020, according to Dow Jones Market Data. A holiday trading environment was blamed for amplifying price swings, in a shortened session on the heels of the U.S. holiday on Thursday. Trading in U.S. oil futures closed an hour early at 1:30 p.m. Eastern. January Brent crude the global benchmark, fell $9.50, or 11.6%, to $72.72 a barrel on ICE Futures Europe, the biggest one-day percentage decline since April 21, 2020. Both WTI and Brent saw their lowest close since Sept. 9.

Oil’s fall, along with sharp losses for U.S stocks as well as European and Asian equities, came after the discovery of a new coronavirus varient with a high level of mutations in South Africa, which has been experiencing a massive spike in cases in recent days.

Some analysts saw the selloff as overdone. “Traders are putting the fear of this new strain ahead of the reality. While we have to take it seriously, oil should find a floor in the $72 area,” said Phil Flynn, analyst at Price Futures Group, in a note.“The worries are still that U.S. volume today will be light but the markets look to be ahead of the risk even though we are not even close to understanding how bad this new variant might be,” he said.

December gasoline fell 12.5% to $2.0294 a gallon, while December heating oil dropped 12.1% to $2.0945 a gallon.

Dubbed the “omicron” variant by the World Health Organization, it had also been detected in Botswana and Hong Kong in travelers who had visited South Africa. The World Health Organization held an emergency meeting on Friday to assess the variant, which scientists aren’t sure is more deadly or to what degree it might be more easily transmissible. But scientists say it is the most heavily mutated variant so far, which could make it more transmissible than the delta variant which plagued the U.S. and Europe in the summer and autumn. Already countries were taking precautionary measures, with the U.K. halting travelers from South Africa and five other nations from Friday. The variant shock comes as Europe has been battling a spike in cases across many countries, such as the economic powerhouse Germany. Austria has locked down its population, while other countries are also rolling out restrictions. “Depending on how this virus-led selloff evolves, and how concerned the WHO is of it, the calculations surrounding the OPEC+ meeting next week could change,” said Jeffrey Halley, senior market analyst at OANDA.

“OPEC+ has stated repeatedly that one area of caution was the resurgence of COVID-19 eroding oil demand as the grouping raises production,” he told clients in a note. Traders have been questioning whether Organization of the Petroleum Exporting Countries and its allies — called OPEC+, will decide next week to scrap those output increases after a coordinated release of strategic reserves by several countries, including the U.S. The cartel and its allies has previously pushed back against requests by the Biden administration and others to speed up production increases. OPEC+ has boosted output in monthly increments of 400,000 barrels a day as it unwinds earlier production cuts.