Omicron has now completely pushed Delta out of many parts of the country, new research shows.
It comes as the World Health Organisation (WHO) warns that more than half of Europe’s population will catch the highly contagious variant in the next six to eight weeks as it sweeps the continent like a “tidal wave”.
The Wellcome Sanger Institute analysed more than 34,000 positive Covid-19 tests taken across England in the week to January 1 to determine which variant they were.
Its weekly monitoring feeds into the wider work done by the UK Health Security Agency.
In more than 30 local authority areas, Omicron was the only variant researchers found. It represented at least 90% of cases in nearly all council areas.
The number of Delta samples found across England has plummeted in the past month, from 98% of tests analysed by the institute in the week to December 4 to just 4% in the week to January 1.
It suggests that Omicron cases are replacing rather than adding to those caused by Delta.
But there are also pockets of the country where the older, more severe variant remains a significant minority of cases, such as in Mid Devon, where nearly a quarter of cases analysed (23%) were found to be Delta.
It is understood that areas still facing a mixture of both Omicron and Delta cases are not causing health officials any more concern than areas where Delta has been driven out.
While Omicron is less likely to make people seriously ill, the sheer scale of infections has seen daily Covid hospital admissions in the UK more than double in a month, putting significant pressure on the NHS.
A spokesperson for the UK Health Security Agency urged people not to “take chances” with the virus, regardless of the variant dominant in their area.
He said: “With Covid-19 infections at record levels and hospital admissions rising, we need everyone to work together to protect our loves ones and our health service.
“That includes taking a lateral flow test before meeting people, wearing a face covering in crowded enclosed spaces, and observing self-isolation guidance if you have symptoms or test positive.
“Don’t take chances with this virus - please get your vaccination or booster jab if you haven’t already.”
The Wellcome Sanger research only covers England, but Omicron is now dominant in every nation of the UK.
In Scotland, Omicron was thought to account for 91.1% of Covid infections on January 5, according to figures published by Public Health Scotland.
In Wales, Omicron accounted for 84% of samples sequenced in the week to January 4.
And ministers in Northern Ireland said on December 30 that Omicron accounted for 90% of cases.
More than half of Europe’s population will catch Omicron in the next six to eight weeks, the WHO has warned.
Dr Hans Henri Kluge, its regional director for Europe, said the highly contagious variant had become “a new west-to-east tidal wave sweeping across the region, on top of the Delta surge that all countries were managing until late 2021”.
He said: “It is quickly becoming the dominant virus in Western Europe and it is now spreading into the Balkans.
“At this rate, the Institute for Health Metrics and Evaluation forecasts that more than 50% of the population in the region will be infected with Omicron in the next six to eight weeks.”
But Dr Kluge said death rates “remain stable and continue to be highest in countries with high Covid-19 incidence combined with lower vaccination uptake”.
A message from the editor:
Thank you for reading. NationalWorld is a new national news brand, produced by a team of journalists, editors, video producers and designers who live and work across the UK. Find out more about who’s who in the team, and our editorial values. We want to start a community among our readers, so please follow us on Facebook, Twitter and Instagram, and keep the conversation going.