US President-elect Joe Biden on Monday urged Americans to wear masks, stressing it is "not a political statement" but the most important step they can take to prevent spread of the deadly coronavirus.

"I implore you, wear a mask.... A mask is not a political statement but it is a good way to start pulling the country together," Biden said in Wilmington after holding a virtual briefing with his Covid-19 advisory council.

Biden, who himself has routinely worn face coverings while campaigning and out in public, said that even as good news of a successful coronavirus vaccine trial has emerged, "the single most effective thing we can do to stop the spread of Covid is to wear a mask."