A group of experts from the World Health Organization are set to arrive in China on Thursday for an investigation into the origins of the coronavirus pandemic.

China's National Health Commission confirmed the upcoming visit in a brief statement Monday, saying the WHO team would be meeting with Chinese scientists to conduct joint scientific research on the virus's origin. It's unclear exactly where they will be carrying out their research and whether they will travel to the central Chinese city of Wuhan, where the novel coronavirus was first detected in December 2019.

The visit follows negotiations between both sides, with WHO Director-General Tedros Adhanom Ghebreyesus expressing disappointment last week over delays with the probe.

Meanwhile, China marked one year on Monday since confirming its first death from COVID-19, the disease caused by the novel coronavirus. China's National Health Commission has since reported more than 87,000 cases of COVID-19 on the Chinese mainland, including at least 4,634 deaths, though those figures are believed to be much higher.

A new, more contagious variant of the novel coronavirus that was first detected in the United Kingdom has now been discovered in Russia.

The strain, called B117, was confirmed among four Russian citizens who had tested positive for COVID-19 upon returning from the U.K., Russia's chief sanitary doctor, Anna Popova, told reporters Sunday evening.

After being identified in Kent in September, B117 has become prevalent in London and other parts of southeast England.

Last month, Russia joined the growing list of countries to suspend flights from the U.K. amid rising COVID-19 infections and concerns about the highly infectious variant there.

With more than 3.3 million confirmed cases of COVID-19, Russia has the fourth-highest tally of diagnosed infections in the world, followed by the U.K., according to a real-time count kept by Johns Hopkins University.

Russia confirmed 23,315 new cases and 436 additional deaths from the disease on Sunday, according to the country's coronavirus headquarters.

ABC News' Alina Lobzina and Patrick Reevell contributed to this report.

Rep. Brad Schneider, D-Ill., said he tested positive for COVID-19 on Tuesday, becoming the third Democrat to do so after sheltering at the Capitol with several Republicans who were unmasked for "several hours” during Wednesday’s siege.

After “narrowly escaping” the violence, Schneider said in a statement, “I was forced to spend several hours in a secure but confined location with dozens of other Members of Congress. Several Republican lawmakers in the room adamantly refused to wear a mask.”

“I am now in strict isolation, worried that I have risked my wife’s health and angry at the selfishness and arrogance of the anti-maskers who put their own contempt and disregard for decency ahead of the health and safety of their colleagues and our staff,” he continued.

Schneider said he hasn't had any symptoms and that he drove home from Washington, D.C., to Illinois.

Rep. Pramila Jayapal and Rep. Bonnie Watson Coleman, both Democrats, have also said they tested positive following the Capitol siege.

Schneider is joining the growing number of Democrats demanding that the House sanction members who don’t wear masks on the House floor.

At a virtual press conference Tuesday, Schneider said, "I don’t know from whom I got this virus or even necessarily if I got it in that room. But I know that my exposure in that room was greater than at any other time through this entire pandemic.”

ABC News’ Ben Siegel and Matthew Vann contributed to this report.