With the US shattering a single-day record with over 1 million Covid-19 cases this week, the Centres for Disease Control and Prevention (CDC) has estimated that the Omicron variant accounted for 95 per cent of new infections last week.

According to new CDC estimates released late on Tuesday, the swing from Delta to Omicron happened in nearly a month.

At the end of November, more than 99.5 per cent of coronavirus infections were Delta in the country.

On Monday, the US shattered a single-day record with over 1 million Covid-19 cases amid the rapid spread of the Omicron variant and government decisions to ease prevention and control measures in the country.

More than 103,000 Americans were hospitalised with Covid-19, the highest number since late summer when the Delta variant of the coronavirus triggered a nationwide surge in cases.

The figure reflected the 27 percent rise in COVID-19 hospitalizations in the United States in the past week. Average daily deaths from Covid-19 declined by 8 percent, reports Xinhua news agency.

Hospitalisation numbers better capture the pandemic’s impact than infection figures, Anthony Fauci, the US Pesident’s chief medical adviser, told ABC’s “This Week”.

The worst day of the pandemic for hospitalisations was January 14, 2021, with more than 142,000.

So far, the US has remained the country worst hit by the pandemic, with the world’s most cases and deaths.

It is heading into the third year of the coronavirus pandemic with the extremely contagious Omicron variant poised to ignite a firestorm of infection across the Southeast after exploding through the Northeast and Mid-Atlantic regions, reported The Washington Post on Tuesday.

“Lower vaccination rates and fewer mask and vaccine mandates have created a much different environment for the Omicron variant to spread in the South, leaving experts unsure whether outbreaks will end up deadlier than in the North,” said the report.

Florida, Georgia, Louisiana, and Mississippi are among the states experiencing the sharpest increases in Covid-19 hospitalisations since Christmas, and “the situation may only get worse, as initial outbreaks in metropolitan areas spread to more poorly vaccinated rural regions,” it said.

Georgia has shattered records, with nearly 1 in 3 tests coming back positive in the last week of December, and in metro Atlanta, nearly half of tests were positive. New daily infections in Florida have hit an average of about 43,000, far above the peak of 23,000 reached during the Delta variant surge in the summer.