?A terrible tragedy?: US passes 800,000 Covid deaths ? highest in the world

The US death toll from Covid-19 has passed 800,000, a once-unimaginable figure seen as doubly tragic given that more than 200,000 of those lives were lost after vaccines became available last spring.

The figure represents the highest reported toll of any country in the world, and is likely even higher.

The US accounts for approximately 4% of the world's population but about 15% of the 5.3 million known deaths from the coronavirus since the outbreak began in China two years ago.

The grim milestone comes as the world braces for rise in cases of the new Omicron variant, with the World Health Organization (WHO) warning it was spreading at an unprecedented rate.

WHO chief Tedros Adhanom Ghebreyesus told reporters on Tuesday the variant had been detected in 77 countries and was probably present in most countries worldwide.

Omicron, first detected by South Africa and reported to the WHO on 24 November, has a large number of mutations, which has concerned scientists. The new variant is posing a fresh threat as it gains a foothold in the US, though experts are not yet sure how dangerous it is.

The number of Covid deaths in the US, compiled and released by Johns Hopkins University on Tuesday, is about equal to the population of Atlanta and St Louis combined, or Minneapolis and Cleveland put together. It is roughly equivalent to how many Americans die each year from heart disease or stroke.