• Scotland, Wales and Northern Ireland have already started new curbs to help stop the spread of the omicron variant, largely focusing on indoor mixing.
• But England has so far held off on adding to current stay-at-home orders and increased mask-wearing.
• Johnson will reportedly digest new data on Monday looking at case rates, hospitalizations and ICU figures, as well as deaths.
• The Christmas holiday meant official figures were paused over the weekend, but on Friday the U.K. reported a record of 122,186 infections over a 24-hour period.

LONDON — U.K. leader Boris Johnson will speak with his top medical advisors on Monday before deciding whether to impose any new Covid-19 restrictions for England this week.

Scotland, Wales and Northern Ireland have already started new curbs to help stop the spread of the omicron variant, largely focusing on indoor mixing. But England has so far held off on adding to current stay-at-home orders and increased mask-wearing.

Johnson will reportedly digest new data on Monday looking at case rates, hospitalizations and ICU figures, as well as deaths. The Christmas holiday meant official figures were paused over the weekend, but on Friday the U.K. reported a record of 122,186 infections over a 24-hour period.

Johnson has previously said that he would not hesitate to act and bring in new curbs after Christmas if needed, but research suggesting that the omicron variant may be less severe than the delta strain could cause him to hold fire. Information on the length of hospital stays and how many infections are leading to hospitalizations will no doubt prove crucial. 

Any new restrictions will likely be unpopular within his own Conservative Party, with many lawmakers staging a recent rebellion against the prime minister. A significant number are unhappy at current Covid restrictions as well as a series of gaffes, scandals and embarrassments in recent weeks. Johnson's ratings have also suffered badly in national voter polls.

New measures would also have to be voted on by the wider House of Commons and lawmakers will have to be recalled from their Christmas vacations. Thus, Johnson may just urge caution to English citizens ahead of New Year's Eve celebrations instead of launching formal restrictions.

A U.K. government study published Thursday said that people are far less likely to be admitted to the hospital with the Covid omicron variant than the previous delta strain.

The U.K. Health Security Agency said individuals with omicron are estimated to be between 31% and 45% less likely to attend emergency departments compared to those with delta, and 50%-70% less likely to require admission to a hospital.

The analysis is "preliminary and highly uncertain" due to the small numbers of omicron cases currently in hospitals, but it does tally with similar findings from scientists in South Africa and research teams at Imperial College London and the University of Edinburgh.

While the number of daily deaths remains low currently and initial research suggests that the omicron variant might not be as severe as other Covid strains, health experts have repeatedly warned that the sheer number of infections could lead to mounting fatalities and an overwhelmed health-care system.

The U.K. has reported nearly 12 million infections and at least 148,324 deaths since the onset of the pandemic in early 2020, according to data complied by Johns Hopkins University.

— CNBC's Ryan Browne contributed to this article.