Coronavirus updates: Herd immunity by fall 'ambitious,' says surgeon general nominee

The University of Michigan has paused all athletics, including men's and women's basketball, for at least 14 days following "several" positive tests by people within the Michigan Athletic Department. The positive tests were also for the so-called U.K. variant, a more-contagious version of the virus. The decision to pause athletics was made in part due to the fact the tests were for the B.1.1.7 variant.

The decision was made not by the school but by the Michigan Department of Health and Human Services. The athletic programs will not be able to play or practice during the period.

"Canceling competitions is never something we want to do, but with so many unknowns about this variant of COVID-19, we must do everything we can to minimize the spread among student-athletes, coaches, staff, and to the student-athletes at other schools," Athletic Director Warde Manuel said in a statement.

The Wolverines men's basketball team, which is currently ranked No. 7 in the latest Associated Press poll, last played Friday against Purdue. Michigan won, 70-53, to advance to 13-1. They currently lead the Big Ten Conference at 8-1. They were supposed to play on Wednesday at Penn State.

The women's basketball team, currently 10-1 overall and ranked No. 11, was supposed to play Purdue on Sunday. The powerhouse men's ice hockey program, ranked in the top 10 nationally, will be affected as well.

The school said no determination has been made on how games scheduled to be played through Feb. 7 will be impacted.

New COVID-19 cases in the U.S. are seeing a "very encouraging" drop, according to The COVID Tracking Project.

The number of weekly cases decreased 21% as of Saturday, the tracker said. There were "more modest but very welcome" drops in COVID-19 deaths and hospitalizations as well. 

The seven-day average for cases is back to "pre-Thanksgiving levels," though the group noted there are still nearly three times as many new cases daily compared to the summer peak.

Los Angeles County has crossed 15,000 deaths, with about one-third of those deaths happening in 2021.

Health officials reported 269 deaths in the county on Saturday. LA remains the hardest-hit county in the United States. LA County has more than twice as many cases (1,064,887) as the second-highest in the nation (Arizona's Maricopa County; 444,431, according to Johns Hopkins University).

The county said 5,106 people have died since Dec. 30.

There was a little bit of good news in LA, however, as the county is following national trends of dropping hospitalizations. The number of people in hospitals with COVID-19 dropped under 7,000 for the first time since Dec. 29, according to the health department.

"Many people continue to spread this virus and, tragically, now more than 15,000 people have died from COVID-19 in Los Angeles County," Dr. Barbara Ferrer, the county's director of public health, said in a statement. "While we are seeing some positive data in daily new cases and hospitalizations, we are far from out of the woods. It is critically important we slow COVID-19 spread to decompress the strain on our healthcare system and save lives."

ABC News' Matthew Fuhrman contributed to this report.

Week-to-week comparisons show new deaths and new cases are on the decline nationwide, according to an internal Department of Health and Human Services memo obtained by ABC News.

Thirty-one states and territories are in a downward trajectory of new cases, according to the memo. Twenty states and territories are in an upward trajectory of new cases while five jurisdictions are at a plateau.

The U.S. saw 1,318,915 new cases from Jan. 16 to Jan. 22 -- a 20.3% decrease from the previous week.

There were 21,442 deaths reported from Jan. 16 to Jan. 22, which was a 7.7% decrease from the week before.

The national test-positivity rate also dropped, falling from 11.9% to 10.4% in week-to-week comparisons, the memo said.

ABC News’ Josh Margolin contributed to this report.