Seychelles, an island nation of just under 100,000 people, has begun immunizing its population against COVID-19 with a vaccine developed by China’s state-owned pharmaceutical company, Sinopharm.

Seychelles President Wavel Ramkalawan became the first African head of state to receive the Sinopharm vaccine on Sunday, as the country officially launched a national COVID-19 immunization campaign -- the first in Africa to do so. The Seychelles Ministry of Health began administering the shot to priority groups on Monday, starting with health care professionals and other front-line workers, according to a press release from the president’s office.

Last month, China authorized Sinopharm's vaccine for general use after the company announced that preliminary data from late-stage trials had shown it to be 79.3% effective. The shot is administered in two doses.

The United Arab Emirates donated 50,000 doses of the Sinopharm vaccine to Seychelles. India offered 100,000 doses of another COVID-19 vaccine developed by England’s University of Oxford and British-Swedish pharmaceutical giant AstraZeneca, which are due to arrive in Seychelles at the end of the month, according to the president's office.

“With such a robust vaccination campaign, Seychelles aims to be the first country in the world to vaccinate at least 70% of its over 18 population,” Ramkalawan said in a statement Sunday. “From there, we will be able to declare Seychelles as being COVID safe. This will allow us to reopen our economy.”

Seychelles, an Indian Ocean archipelago located off the coast of East Africa, has reported 508 confirmed cases of COVID-19 since the start of the pandemic, including at least one death, according to the latest data from the Africa Centers for Disease Control and Prevention.

There were 213,905 new cases of COVID-19 confirmed in the United States on Sunday, according to a real-time count kept by Johns Hopkins University.

It's the sixth straight day that the country has reported more than 200,000 newly confirmed infections. Sunday's tally is less than the all-time high of 302,506 new cases, which the country logged on Jan. 2, Johns Hopkins data shows.

An additional 1,814 new deaths from COVID-19 were also registered nationwide Sunday, down from the country's peak of 4,194 fatalities on Jan. 7, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the holidays followed by a potentially very large backlog.

A total of 22,409,131 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 374,329 of them have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4 and reaching 200,000 for the first time on Nov. 27.

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.

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.