Oil prices were lower on Friday in quiet trade due to the US Thanksgiving holiday, falling amid worries regarding oversupply about a vaccine to end the coronavirus pandemic.Brent crude dropped 31 cents, or 0.7%, at $47.49 by 0758 GMT, having dropped 1.7% overnight. West Texas Intermediate fekk by $1.02, or 2.2%, at $44.69. US crude prices did not settle on Thursday due to the holiday.Both benchmarks have increased roughly 6% this week after AstraZeneca announced that its coronavirus vaccine could be up to 90% effective, adding to successful results for two others under development in the battle to end the pandemic.But questions have been raised regarding the “vaccine for the world”, with several scientists sounding concerns over how strong the results for the trials were.