Professor Chris Whitty, the Chief Medical Officer for England said, "We have alerted the World Health Organisation and are continuing to analyse the available data to improve our understanding".
Johnson also held emergency talks with the first ministers of Britain's devolved governments in Scotland and Wales.
"As introduced on Monday, the United Kingdom has recognized a brand new variant of Covid-19 by way of Public Well being England's genomic surveillance", Whitty mentioned in a press release.
Giroir, a member of the White House coronavirus task force, urged President Donald Trump to get vaccinated against Covid-19 to promote acceptance of immunization among his supporters.
More than 1.98 million people have tested positive for the coornavirus in the UK.
Variations of the virus in South Africa and the south-east of England, where case numbers are surging, have also caused worldwide concern. Household mixing will be banned in London and southeast England, and socializing will be restricted to just Christmas Day across the rest of England.
"I don't think there's any reason for alarm right now", agreed Admiral Brett Giroir, the U.S. official overseeing coronavirus testing, when asked about the new variant on ABC's "The Week".
A mutation is referred to as a change in the genetic sequence of the virus. There have been many mutations in the virus since it emerged previous year in Wuhan, China, with 4,000 mutations in the spike protein alone.
Interest In Taking Coronavirus Vaccine Increases
Bush - have said they too will be getting vaccinated and offered to do it on TV. President-elect Joe Biden will receive a public vaccination next week.
"When the virus changes its method of attack, we have to change our method of defence", said Johnson during the press conference.
Like other countries in Europe, Britain is battling to contain new waves of the virus.
"We absolutely need to stick to the basics of making sure that we reduce our contacts, reduce the ability for this virus to spread, and that's the reason that tougher measures are required to keep their variant under control".
The British capital London and parts of southern England will have to go into lockdown again a few days before Christmas.
Scientists subsequently discovered that the new strain was "much more transmissible than the other variants in circulation", Dr Hopkins said. Absent a more timely and holistic response on the part of both the public and private sectors, we risk a lot more damage - both temporary and durable - in the remaining voyage to herd immunity and the related return to better public health and more normal economic and social interactions.
The number of cases now stands at 2,040,147.
According to the government's scientific advisers, the new strain is fast becoming the dominant strain, and they said it might be present in other countries.