Oil prices ended slightly down on Thursday, in the face of the worsening of the Covid-19 epidemic but also because of tensions over quotas within OPEC.

The North Sea Brent crude contract for January delivery fell 0.31% or 14 cents, from Wednesday's close at $44.20.

In New York, the US barrel of WTI for December fell 0.19% or 8 cents to $41.74.

Prices, which had lost more during the session, recovered a little at the close.

“We are witnessing a speed race between Covid and vaccines,” summarized Robert Yawger of Mizuho USA. “Between the rise in Covid-19 cases and the closure of New York schools, it is getting worse. At the same time, there is hope for the future with vaccines,” he explained.

After the good news on the spectacular effectiveness of future vaccines from Pfizer and Moderna, it was the turn of the British laboratory AstraZeneca to announce encouraging results of its vaccine in the elderly.

The United States has reached the bar of 250,000 deaths attributed to the coronavirus since the start of the pandemic.

And the epidemic has started to rise again significantly in recent weeks among the first consumer of black gold.

Added to this are "the tensions within OPEC +", underlined Eugen Weinberg, analyst at Commerzbank.

The Organization of Petroleum Exporting Countries (OPEC) and their allies via the OPEC+ agreement said they were "ready to act" on Tuesday to maintain a balance between supply and demand for black gold, at the end of their monthly meeting.

But it seems that the United Arab Emirates "are not happy" and do not want to extend their production cuts, explained Robert Yawger. "It's a bit worrying before the next OPEC meeting" at the end of November. The analyst, however, believes that ultimately the production restrictions will be extended by mutual agreement even if after the fact some may "cheat".

The Emirates can produce up to 4 million barrels per day but their current quota would be 2.6 mbd.

Members of the producer alliance meet at the end of the month to decide how much crude will return to the market on January 1, or later, in what is shaping up to be the next "big risk event for the oil," said Jeffrey Halley of Oanda.