The US stands on the brink of a once-unthinkable tally: 500,000 people lost to the coronavirus.

A year into the pandemic, the running total of lives lost is 498,897 - roughly the population of Kansas City, Missouri, and just shy of the size of Atlanta.

The figure compiled by Johns Hopkins University surpasses the number of people who died in 2019 of chronic lower respiratory diseases, stroke, Alzheimer's, flu and pneumonia combined.

America's top infectious disease expert Dr Anthony Fauci told CNN: "It's nothing like we have ever been through in the last 102 years, since the 1918 influenza pandemic."

The US virus death toll reached 400,000 on January 19 in the waning hours in office for president Donald Trump, whose handling of the crisis was judged by public health experts to be a failure.

The first known deaths from the virus in the US happened in early February 2020, both of them in Santa Clara County, California.

It took four months to reach the first 100,000 dead. The toll hit 200,000 deaths in September and 300,000 in December.

Then it took just over a month to go from 300,000 to 400,000 and about two months to climb from 400,000 to the brink of 500,000.

US president Joe Biden will mark the grim milestone with a moment of silence and a candle-lighting ceremony at the White House.

The White House said Mr Biden will deliver remarks at sunset to honour those who lost their lives.

He will be joined at the event by first lady Jill Biden and vice president Kamala Harris and her husband, Doug Emhoff.

Mr Biden has made a point of recognizing the lives lost from the virus. His first event upon arriving in Washington for his inauguration a month ago was to deliver remarks at a Covid-19 memorial ceremony.

Joyce Willis of Las Vegas is among the countless Americans who lost family members during the pandemic. Her husband, Anthony Willis, died on December 28, followed by her mother-in-law in early January.

She was unable to see him in hospital before he died because she, too, had the virus and could not visit.

"They are gone. Your loved one is gone, but you are still alive," Mrs Willis said.

"It's like you still have to get up every morning. You have to take care of your kids and make a living. There is no way around it. You just have to move on."

Then came a nightmare scenario of caring for her father-in-law while dealing with grief, arranging funerals, paying bills, helping her children navigate online school and figuring out how to go back to work as an occupational therapist.

The global death toll is approaching 2.5 million, according to Johns Hopkins.

While the count is based on figures supplied by government agencies around the world, the real death toll is believed to be significantly higher, in part because of inadequate testing and cases inaccurately attributed to other causes early on.

Despite efforts to administer coronavirus vaccines, a widely cited model by the University of Washington projects the US death toll will surpass 589,000 by June 1.

"People will be talking about this decades and decades and decades from now," Dr Fauci said later on NBC's Meet The Press.