London, Omicron is now the predominant variant among new cases of Covid in England, and is also causing reinfection around one in 20 cases, according to new analysis published by the UK Health Security Agency (HSA).

Of 5,153 individuals identified with an Omicron infection between November 1 and December 11, 305 (5.9 per cent) were linked to a previously confirmed infection and also had an interval from the previous positive test of 90 days or more.

"The data so far suggests an increase in overall reinfection rates, alongside an increase in first infections" the HSA said in a statement.

The ages of the cases linked with a previous infection ranged from six to 68 years old, while there were four people for whom omicron was their third episode of infection.

While Omicron is now the predominant variant, there is still considerable variation in the estimated levels of Omicron for different regions, the Telegraph reported.

According to data published by the UKHSA, some 54.2 per cent of a sample of new Covid cases across England with specimen dates for December 14 and 15 were found to have S gene target failure (SGTF) - a way of detecting the likely presence of omicron.

Most samples of Omicron that have been sequenced in a laboratory have been found to contain a slight but identifiable difference from other Covid variants such as delta.

This difference -- a deletion in the S gene -- shows up in certain laboratory PCR tests and can be used as a way of estimating the spread of Omicron.

The figures also show that 80.8 per cent of a sample of detectable cases in London from December 14 and 15 were classed as SGTF, along with 62 per cent in eastern England and 55.9 per cent in south-east England.

Meanwhile, the UK recorded a further 93,045 Covid-19 cases on Friday, the highest daily total since the start of the pandemic as the omicron wave continues to surge.

Omicron cases increased by 3,201, or 27 per cent.

Further, the UKHSA also revealed that the lateral flow (LFD) tests are as likely to detect Omicron as other variants of coronavirus.

"Our data shows that LFD tests are similarly able to detect Covid-19 in individuals who have been exposed to Omicron as in those exposed to previous variants. This is very encouraging," said Dr Jenny Harries, HSA chief executive, in a statement.

"As we all work to limit the high levels of transmission of this variant over the Christmas period, we are urging people to test regularly, particularly before attending social gatherings.

"As always, the booster vaccine remains the best protection against infection. Please come forward to receive your booster as soon as possible," she said.

UK Prime Minister Boris Johnson on Friday said the country is facing a "considerable wave" of the Omicron variant as he urged people to get their Covid booster jabs, the Telegraph reported.

"Omicron is a very serious threat to us now," he was quoted as saying.

"We are seeing a considerable wave coming through and people have got to be prepared and they have got to understand what it entails.

"That's why the best thing everybody can do is not just follow the guidance we have set out but get boosted now," Johnson said.