Some 22 cases of the new Omicron variant have now been confirmed in the UK.
Experts have raised fears that the new variant could spread faster than existing strains, and could evade some of the protection offered by current Covid vaccines.
Speaking in the House of Commons on Wednesday, Sajid Javid warned that case numbers would increase.
The health secretary said “we have to be realistic” that there is already likely to already be transmission of Omicron within the community.
Where have cases of Omicron been found?
The map below shows the areas of the UK where at least one case of Omicron has been confirmed.
The full list of areas where a case has been detected is as follows:
Barnet: 2 cases
Brentwood: 1 case
Camden: 2 cases
Greater Glasgow and Clyde: 4 cases
Haringey: 1 case
Lanarkshire: 5 cases
Liverpool: 1 case
North Norfolk: 1 case
Nottingham: 1 case
Sutton: 1 case
Wandsworth: 1 case
Westminster: 2 cases
The government has reintroduced some Covid restrictions to curb the spread of the variant, as well as extending the scope of the booster vaccine campaign.
The mandatory wearing of face coverings in shops and on public transport came into force in England on Tuesday morning, along with tighter testing requirements for international travel and the return of self-isolation for contacts of confirmed Omicron cases, even if they have been fully vaccinated.
The PM also pledged that everyone over the age of 18 will be offered a booster jab by the end of January.
Previously the third dose was only available to people over the age of 40, health workers, and people who are clinically vulnerable to coronavirus.
Johnson used a Downing Street press conference to promise another “great British vaccination effort” to deliver millions of jabs.
“We’re going to be throwing everything at it, in order to ensure that everyone eligible is offered that booster in just over two months,” he said.
Javid said on Wednesday morning that the NHS is working to suspend some of the workload of GPs so they can concentrate on the vaccination programme.
“The NHS is working on that right now with GP representatives,” he told BBC Breakfast.
“I am confident that they will work out a way where some of the workload of GPs can be temporarily suspended or GPs can be helped in other ways so they can concentrate on vaccine delivery.”
He urged people who were struggling to book a booster jab to contact their MP.
“If they have contacted their GP and they are not getting anywhere, the best they can do right now is probably contact their Member of Parliament directly and that will come to me and we will do everything we can to help,” he said.