Omicron restrictions are required for at least two months, according to the top health official.
Dr Susan Hopkins, the chief of the UK Health Security Agency, has told MPs that Plan B restrictions should be extended into the new year.
It happened as she was explaining to the House Committee on Health and Science why boosters are the country's only hope against rising Omicron cases, and why the new variant has caused so much concern.
MPs voted on incoming coronavirus rules and restrictions this afternoon.
"We would need some level of restrictions in place for the next four to eight weeks," Dr Hopkins said when asked how long she thought the rules would be in place.
In most public venues, including cinemas and theaters, the public has been required to wear a face covering since Friday unless exempted.
To help stop the spread of Omicron, the government has advised Brits to work from home where they can, with a record number of Covid vaccines administered yesterday.
Vaccine passports are now required as a condition of entry for large venues, with a negative test within the last 48 hours or proof of vaccination required upon entry.
The government has replaced the 10-day self-isolation period for those exposed to the Omicron variant with a new seven-day testing regime as of today.
Brits have been urged to get their booster shot as soon as possible to avoid contracting the new strain.
The push for vaccinations comes after Cabinet ministers were warned that Omicron cases could overwhelm hospitals by the middle of January.
Ministers have been warned that by January 15, so many NHS doctors and nurses will be sick that some hospitals may be forced to close.
Even by "the most conservative" estimates, the PM and Government medics told the virtual cabinet this morning that things are looking "very bad" when it comes to cases.
The growth of Omicron cases in the UK is "now mirroring the rapid increase we're seeing in South Africa," according to Health Secretary Sajid Javid, who added that "the current observed doubling time is around every two days."
"While we reported 4,713 confirmed Omicron cases in the UK yesterday, the UKHSA estimates that the number of daily infections is 42 times higher, at 200,000."
"Scientists have never seen a Covid-19 variant capable of spreading at such a rapid rate, so we need to figure out how to slow Omicron's spread."
Moderna's chief medical officer, Dr. Paul Burton, has also issued a warning to the government about the rise in Omicron cases.
"These two viruses will coexist in the near future," Dr Burton predicted.
"Omicron is going to infect people who have a lot of Delta in their system."
I believe Omicron is a serious threat; its three-day doubling time is much faster than anything else we've seen.
"Both viruses can be carried by people, and this could happen here; it could be [much worse]"
The two viruses "could share genes and swap genes over," he added.
It's unclear whether this would worsen an infection, but it could cause problems for future variant developments, according to Dr Burton.