Vehicles run on Regent Street decorated with Christmas lights in central London, Britain, on Nov. 20, 2021. (Xinhua)

At least one person has died in the UK after contracting the Omicron coronavirus variant, Prime Minister Boris Johnson said on Monday, the first publicly confirmed death globally from the swiftly spreading strain.

Since the first Omicron cases were detected on November 27 in Britain, Johnson has imposed tougher restrictions and on Sunday cautioned that the variant could overcome the immune defenses of those inoculated with two shots of vaccines.

Britain gave no details on the death other than the person had been diagnosed in hospital. It was not clear if the patient had been vaccinated or had underlying health issues.

Deaths from Omicron may have occurred in other countries but none has been publicly confirmed yet outside Britain.

"Sadly at least one patient has now been confirmed to have died with Omicron," Johnson told reporters at a vaccination center in London.

"So I think the idea that this is somehow a milder version of the virus - I think that's something we need to set [to] one side - and just recognize the sheer pace at which it accelerates through the population."

Health Secretary Sajid Javid said the variant now accounted for 44 percent of infections in London and would be the dominant strain in the capital within 48 hours. New Omicron infections are estimated at 200,000 per day, Javid said.

Before the death was announced, Britain said 10 people had been hospitalized with Omicron in various parts of England. Their ages ranged from 18 to 85 and most had received two vaccination doses.

The UK Health Security Agency said Omicron - first detected in South Africa, Botswana and Hong Kong, China in late November - can overcome the immunity of those who have had two shots of vaccines such as AstraZeneca or Pfizer-BioNTech.

South Africa's health ministry said it was unable to say with certainty if any of its COVID-19 deaths were caused by Omicron as deaths were not broken down by variant.

The World Health Organization said on Sunday that while preliminary findings from South Africa suggest Omicron may be less severe than the Delta variant - currently dominant worldwide, and all cases reported in the Europe region have been mild or asymptomatic, it remains unclear to what extent Omicron may be inherently less virulent. 

Johnson, now grappling with a rebellion in his party over measures to curb Omicron and an outcry over staff parties at his Downing Street office during 2020's lockdowns, said people should rush to get booster vaccines to protect "our freedoms and our way of life."

Reuters