London: London and its surrounding areas will be placed under Britain's highest level of coronavirus restrictions beginning Wednesday as infections rise rapidly in the capital, the health secretary said Monday, adding that a new variant of the virus may be to blame for the spread.

Britain's health secretary Matt Hancock said Monday that the government must take swift action after seeing “very sharp, exponential rises” in Greater London and nearby areas. Under Tier 3 restrictions, the toughest level, people can’t socialize indoors and bars, pubs and restaurants must close except for takeout. He said in some areas cases are doubling every seven days.

Hancock told lawmakers that officials have identified “a new variant of coronavirus which may be associated with the faster spread in the south of England.” He said so far, about 1,000 cases of the variant have been identified in England, and they have alerted the World Health Organization.

“We’ve currently identified over 1,000 cases with this variant predominantly in the south of England, although cases have been identified in nearly 60 different local authority areas,” he said. Initial analysis suggests that the new variant is growing faster than existing variants, he added.

“The medical advice that we have is that it is highly unlikely that this new variant will impinge the vaccine and the impact of the vaccine,” he said.

The World Health Organization is among those studying the new virus strain, which has been identified in other countries in recent months.

Britain started vaccinating people over age 80 and health care workers on Dec. 8 with the Pfizer-BioNTech vaccine and its regulators are also evaluating other vaccines, including one developed by AstraZeneca and Oxford University. Thousands have been vaccinated so far, but they must return in 21 days for a second shot. The National Health Service said hundreds of medical clinics across England were getting vaccine deliveries on Monday and would be offering shots by Tuesday.

Under Tier 3 restrictions, the toughest level in England’s three-tier system, people can't socialize indoors, and bars, pubs and restaurants must close except for takeout. People are told to minimize traveling within or to the area, and Hancock said people shouldn't take trips into central London to do Christmas shopping.

London is currently in Tier 2, or high alert, which applies to most of England.

Dr Michael Ryan, the chief of emergencies for the World Health Organization, said the UN health agency was aware of the new strain reported in the UK and was working with British and other health authorities to assess if the reported mutations might change how the virus is behaving.

(With inputs from agency)