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.

COVID-19 cases continue to be significantly lower in younger kids, even as some went back to school in-person, according to a new report from the Centers for Disease Control and Prevention.

The incidence of COVID-19 in children, particularly those ages 0 to 10, has been lower than that of young adults and adults throughout the entire second half of 2020, according to the CDC. The incidence of COVID-19 cases in kids was higher as the age increased.

While older teenagers and young adults saw a surge of cases near the beginning of the school year, this was not seen in younger kids, "suggesting that young adults might contribute more to community transmission than do younger children," the report said.

Children also had significantly lower rates of hospitalizations, intensive care unit stays and death than adults, the study found.

Fewer COVID-19 tests are performed on children, so the actual incidence may be higher than the data that's available.

Teacher and school employee transmission risk also were not included in the data.

The CDC continues to recommend strict mitigation strategies to prevent transmission in schools that are in-person.

-ABC News' Dr. Rose Marie Leslie