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.

Weeks after video emerged of mostly maskless partygoers at U.S. President Donald Trump's Mar-a-Lago Club in Palm Beach, county officials are cracking down.

Palm Beach County sent a letter this week, acquired by ABC News, warning the club and saying officials had met with representatives from the club about violations. Masks are mandatory in the county in all businesses or establishments, and anywhere in public social distancing cannot be maintained. The mandate is currently in place through Jan. 20 -- the same day the county's most famous resident will be exiting the White House.

"Thank you for meeting with us last week to discuss the concerning allegations regarding the Mar a Lago New Year's Eve party and lack of facial coverings being worn during evening activities," the county wrote in the letter addressed to Bernd Lembcke, executive vice president and managing director of Mar-a-Lago Club.

"We recount that you provided masks for all party goers who attended the party and that you provided additional masks for those that walked from the reception area to the main dining ballroom," the letter continued. "Although you provided these important steps, it seemed that based on the video evidence, there was a breakdown in enforcement of the mask orders that led to almost the entire room of guests being without masks during the later evening activities."

The letter also includes a confirmation of the violation, which is a first-time warning, that lays out a fine of up to $15,000 for each potential future violation.

Trump has consistently downplayed wearing masks over the course of the entire pandemic. Despite telling people to wear masks on occasion at official briefings, he also mocked others for wearing them, including President-elect Joe Biden. Many supporters have decried mandates and openly flouted rules, including maskless Trump supporters who stormed the Capitol last week.

ABC News' Will Gretsky contributed to this report.