• Confirmed cases of the coronavirus in the U.S. topped 11 million over the weekend.
• Richard Clarida, vice chairman of the U.S. Federal Reserve, is expected to make a speech at 12 p.m. ET.

U.S. Treasury yields declined on Monday as rising coronavirus cases remained a concern for investors, despite last week's news of an effective vaccine against the virus.

The yield on the benchmark 10-year Treasury note fell to 0.878% at 4:52 a.m. ET, while the yield on the 30-year Treasury bond slid to 1.628%. Yields move inversely to prices.

Treasury yields slumped as confirmed cases of the coronavirus in the U.S. topped 11 million over the weekend, according to data compiled by Johns Hopkins University.

This is despite the news last week that a coronavirus vaccine, developed by Pfizer and BioNTech, was found to be more than 90% effective in preventing Covid-19 among those without evidence of prior infection.

Meanwhile, President Donald Trump publicly acknowledged that President-elect Joe Biden had won the U.S. election for the first time on Sunday. "He won because the Election was Rigged," Trump wrote on Twitter but followed this up with a tweet that said he had conceded "NOTHING."

November data for the New York Empire State Manufacturing Index is due out at 10:30 a.m. ET on Monday.

Richard Clarida, vice chairman of the U.S. Federal Reserve, is expected to make a speech at 12 p.m. ET and San Francisco Fed President Mary Daly is then set to speak at 1:45 p.m. ET.

Auctions will be held Monday for $54 billion worth of 13-week bills and $51 billion of 26-week bills.

— CNBC's Tucker Higgins and Spencer Kimball contributed to this story.