The world hit a record number of Covid infections in a seven-day period, with more than 935,000 cases detected on average each day between 22-28 December, according to an AFP tally.

The figures, the highest since the virus first emerged at the end of 2019, are based on tolls given daily by health authorities in each country.

A large share of the less serious or asymptomatic cases remain undetected despite ramped up testing in many countries since the pandemic began. 

Also, testing policy varies from one country to another.

With 6,550,000 cases recorded between 22 December and 28 December -- or an average of 935,863 a day -- the virus is spreading at unprecedented speed.

The figures are sharply higher than the previous record between 23-29 April when 817,000 cases were recorded on average each day.

The detected infections, which have been rising globally since mid-October, increased by 37 percent over the preceding seven days.

"The rapid growth rate is likely to be a combination of both immune evasion and intrinsic increased transmissibility of the Omicron variant," the World Health Organization said Tuesday.

"The overall risk related to the new variant of concern Omicron remains very high," the UN health agency added.

For now, the explosion in detected case numbers has not led to a worldwide increase in deaths, which have been on the decline for the last three weeks.

Around 6,450 new deaths a day have been recorded on average in the last seven days, the lowest since the end of October 2020.

At the height of the pandemic, 14,800 daily deaths were recorded between 20-26 January 2021.

Most of the new infections are currently occurring in Europe, where more than 3.5 million cases have been recorded in the last seven days, or more than 510,000 on average each day.

The level is also unprecedented, as the continent never recorded more than 300,000 cases per day in previous waves.

In the two years sine the virus was discovered, more than 282 million cases of Covid-19 have officially been detected in the world, with more than 5.4 millions deaths. 

Taking into account excess mortality linked to Covid-19, the World Health Organization estimates the overall death toll could be two to three times higher.