US President Joe Biden ordered all flags on federal property be lowered to half-staff for the next five days to mark the bleak milestone.

He also paid tribute to those who died from the virus and said: “As of this week during the dark winter of the Covid-19 pandemic, more than 500,000 Americans have now died from the virus.

“That is more Americans who have died in a single year of this pandemic than in World War I, World War II, and the Vietnam War combined.

“On this solemn occasion, we reflect on their loss and on their loved ones left behind. We, as a nation, must remember them so we can begin to heal, to unite, and find purpose as one nation to defeat this pandemic.”