The new coronavirus measures are set to be reviewed just days before Christmas.
Eight further cases of the Omicron variant have been confirmed in England, bringing the total number identified in the country to 13, the UK Health Security Agency (UKHSA) said.
Nine cases have also been identified in Scotland, meaning 22 cases have been identified across the two countries.
The new strain, which has mutated in such a way that scientists fear it may be able to evade the vaccine, has caused the UK Government to reassess its Covid measures.
On Wednesday, masks will be compulsory in shops and on public transport, PCR tests must be taken by international arrivals and all close contacts of an omicron case must self-isolate, regardless of vaccine status.
The new restrictions are due to be reviewed in three weeks with most of them to be looked at on December 20.
As a result the Government has space to bring in additional measures before Christmas if the situation worsens.
Health Secretary Sajid Javid says that schedule is not set in stone and that "we won’t keep measures in place for a day longer than necessary" if the landscape changes.
UKHSA said that there were now two cases in Barnet, one in Brentwood, two in Camden, one in Haringey, one in Liverpool, one in north Norfolk, one in Nottingham, one in Sutton, another in Wandsworth and two in Westminster.
In a bid to tackle the new strains' spread, the Government is speeding up its booster campaign.
On Tuesday, Boris Johnson announced that he wanted all UK adults to have had a booster jab by the end of January.
The Prime Minister said at least 400 military personnel will help the NHS and volunteers deliver jabs, with centres "popping up like Christmas trees".
Mr Johnson told a Downing Street press conference: "We've already done almost 18 million boosters across the UK but we've got millions more to do to protect the most vulnerable.
"Then we'll move down the cohorts rapidly, and working together with the devolved administrations we want to ramp up capacity across the whole United Kingdom to the levels we achieved in the previous vaccination effort.
"We're going to be throwing everything at it in order to ensure that everyone eligible is offered that booster, as I say, in just over two months."
