An international team of 13 scientists researching the origins of COVID-19 arrived Thursday in Wuhan, China, where the novel coronavirus was first discovered, according to the World Health Organization.

"The experts will begin their work immediately during the 2 weeks quarantine protocol for international travelers," the WHO wrote on Twitter.

All team members had to be tested for COVID-19 again in Singapore before flying to China. The polymerase chain reaction (PCR) tests were all negative, but two IgM antibody tests returned positive results. Those two scientists remain in Singapore as they are retested, according to the WHO.

A total of 965,000 workers in the United States filed jobless claims last week, the U.S. Department of Labor said Thursday, an increase of 181,000 from the prior week.

The Labor Department also said that more than 18 million people were still receiving some form of unemployment benefits through all government programs for the week ending Dec. 26. For the comparable week in 2019, that figure was just above 2 million.

The weekly unemployment tally has fallen since peaking at 6.9 million in March but still remains elevated by historical standards.

The pre-pandemic record for weekly unemployment filings was 695,000 in 1982.

That record has been broken every week since late March.

As of last month, the unemployment rate in the U.S. was 6.7%. It was 3.5% last February.

-ABC News’ Catherine Thorbecke contributed to this report

This week’s national ensemble forecast released by the U.S. Centers for Disease Control and Prevention predicts that 16,200 to 29,600 more Americans will likely die from COVID-19 in the week ending Feb. 2.

The national ensemble estimates a total of 440,000 to 477,000 deaths from the disease will be reported nationwide by that date.

Nearly all U.S. metro areas with over 500,000 people are in "full resurgence" of COVID-19, the White House coronavirus task force said in its latest report, obtained by ABC News Wednesday.

In the report, dated Jan. 10, the task force said the fall/winter surge has had nearly twice the rate of rise in COVID-19 cases as the spring and summer surges.

Several states, including Arizona, California, Florida, Georgia, Louisiana, New Mexico and South Carolina, are also in "full pandemic resurgence," the report stated.

Only "aggressive mitigation" can "match a more aggressive virus," and Americans must take more precautions, "moving beyond what worked in the summer to more layered mitigation," the report stated.

The task force recommended uniform mask implementation and "strict physical distancing." Without that, "epidemics could quickly worsen as more transmissible variants spread and become predominant," it warned.

ABC News' Josh Margolin and Brian Hartman contributed to this report.

U.S. President-elect Joe Biden has chosen Dr. David Kessler, former commissioner of the Food and Drug Administration (FDA), to help lead the federal government's COVID-19 vaccine initiative.

Kessler, a pediatrician and lawyer who headed the FDA from 1999 to 1997 under the Bush and Clinton administrations, will replace Dr. Moncef Slaoui, who is the current chief science officer to Operation Warp Speed.

Biden also announced several other appointees who will join his incoming administration's COVID-19 response team.

"We are in a race against time, and we need a comprehensive strategy to quickly contain this virus," Biden said in a statement Thursday. "The individuals announced today will bolster the White House’s COVID-19 Response team and play important roles in carrying out our rescue plan and vaccination program. At a time when American families are facing numerous challenges I know these public servants will do all that is needed to build our nation back better."