The UK is to close all travel corridors from Mon morning to "drive back the risk of up to now unidentified new strains" of Covid, the PM has said.
Anyone flying into the country from overseas must show evidence of a negative Covid test before setting off.
It comes just as a ban in travellers from South America and Portugal came into force on Friday over concerns about a new variant discovered in Brazil.
Boris Johnson said the new rules would be set up until at least 15 February.
A further 1,280 persons with coronavirus possess died in the UK within 28 times of a positive test, taking the total to 87,291.
The latest government figures on Friday also showed another 55,761 new cases have been reported - up from 48,682 the prior day.
Meanwhile, a lot more than two million people all over the world have now died with the virus because the pandemic began, according to statistics from Johns Hopkins University.
Speaking by a Downing Street press meeting, the prime minister explained it had been "vital" to have extra methods now "when daily we are making these kinds of strides in safeguarding the population".
"It's precisely because we've the hope of this vaccine and the chance of new strains coming from overseas that we must take additional actions now to stop those strains from getting into the country."
All travel corridors will close from 04:00 GMT on Monday. From then on, arrivals to the UK will have to quarantine for 10 times, unless they test bad after five days.
Mr Johnson, who said the rules would apply over the UK after talks with the devolved administrations, added that the government would be stepping up enforcement at the border and in the country.
Travel around corridors were introduced found in the summertime to allow people travelling from some countries with low amounts of Covid conditions to come quickly to the UK and never have to quarantine on arrival.
Trade body Airlines UK said it supported the most recent restrictions "in the assumption" that the government would remove them "when it is safe to take action".
Leader Tim Alderslade reported travel corridors were "a lifeline for the industry" last summer but "things change and there is no doubting this is going to be a serious health emergency".
Labour innovator Sir Keir Starmer said it had been the "right step" but called the timing of your choice "slow again", adding that the general public will be thinking "why on the planet didn't this happen before".
The prime minister warned that the NHS was facing "extraordinary pressures", having had the best number of hospital admissions about the same day of the pandemic earlier this week.
He said that came on Tuesday when there were 4,134 new admissions, as the UK currently has a lot more than 37,000 Covid patients in hospitals.
Mr Johnson said that once the most vulnerable have already been vaccinated by mid-February "we will think about what techniques we could take to lift the restrictions".
England is currently under a national lockdown, meaning persons must stay at home and can venture out only for limited causes such as for example food shopping, exercise, or work if indeed they cannot do so from home.
Similar measures are set up across a lot of Scotland, Wales and Northern Ireland.