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.

Pope Francis and his predecessor, Pope Emeritus Benedict XVI, have received their first dose of a COVID-19 vaccine, according to Vatican spokesman Matteo Bruni.

"I can confirm that as part of the Vatican City State vaccination program to date, the first dose of the COVID-19 vaccine has been administered to Pope Francis and the Pope Emeritus," Bruni said in a statement Thursday.

Francis, who turned 84 last month and had part of a lung removed when he was younger, reportedly received the shot Wednesday while Benedict, 93, reportedly got it Thursday.

Vatican City, an independent enclave surrounded by Rome that serves as the headquarters of the Roman Catholic Church, launched the immunization campaign on Wednesday, administering doses of a COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech.

The tiny city-state has a population of only around 800 people but employs more than 4,000. It's unclear how many doses of the Pfizer/BioNTech vaccine have been procured so far.

Vatican City citizens, along with employees and pensioners, will have the opportunity to receive the vaccine as well as family members who are entitled to use of the city-state's health care system. Priority is being given to health care workers, public safety personnel, the elderly and individuals who are most frequently in contact with the public, according to Bruni.

The vaccination campaign is voluntary and people under the age of 18 are being excluded for the time being, Bruni said.

Since the start of the pandemic, Vatican City has reported at least 27 confirmed cases of COVID-19, according to a real-time count kept by Johns Hopkins University.

ABC News' Phoebe Natanson contributed to this report.