Boris Johnson has already been forced to introduce social restrictions to combat the new Omicron variant of the coronavirus and rocketing infection numbers this month could see him forced to tighten them still further with Christmas just days away.

       The prime minister has already brought back mandatory mask-wearing on public transport and in shops, cinemas, theatres and places of worship, asked citizens to work from home where possible and made an NHS Covid Pass or negative lateral flow test a necessary requirement for entry to crowded venues and events involving mass gatherings.

       Even so, fears persist that strongers measures may yet be needed to beat back Omicron, with government scientific advisers pushing for new restrictions as soon as possible to stop the spread and meeting opposition from senior Cabinet ministers reluctant to jeopardise the economy and impose further constraints on public freedom.

       The prime minister has said he will “reserve the possibility” of a tighter clampdown, which does not currently look likey to be enforced this week, and is understood to be waiting for more data on Omicron to become available before he makes a decision, a stance that has seen him accused of “dithering” by opponents.

       The precise characteristics of the new strain of the virus are still not clear at this early stage in its development, although it is feared it may soon usurp the Delta variant as the dominant strain of Covid-19 given its high transmissibility.

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       Mr Johnson recently warned the public that a “tidal wave” of infections could break on these shores unless people adhere to the new measures, exercise extreme caution and get their vaccine booster jab as a matter of urgency.

       The rollout of third shots is being greatly expanded to address the Omicron threat, with the aim of offering one to all over-18s by the end of December, bringing forward that deadline by a month and placing further pressure on medical professionals across the country in the process.

       That decision came in response to findings by the UK Health Security Agency indicating that two jabs do not offer strong protection against symptomatic infection from Omicron, with the current suite of vaccines less effective against it than they were against Delta.

       However, that same analysis also concluded that those who had received a booster remained up to 70 per cent protected, underlining the importance of getting a third shot as soon as possible.

       The UK has recorded 12 deaths from the new variant so far and 45,145 confirmed cases.

       London mayor Sadiq Khan has declared a major incident over the extent of the Omicron outbreak in the capital while NHS England has announced a return to its highest level of emergency preparedness, level four national incident, meaning that the health service’s response will be coordinated as a national effort, rather than led by individual trusts.

       Overall, the UK added another 91,743 infections in 24 hours on Monday 20 December plus a further 44 fatalities, a slight fall from the pandemic high of 93,045 recorded the preceding Friday.

       Meanwhile, just 50.4 per cent of British adults have had their booster injection so far, although demand is high so that figure should continue to climb rapidly as more people make an appointment and roll up their sleeves.

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       The PM is not currently scheduled to hold a Covid press briefing on Tuesday 21 December but that could change as the day progresses.

       The usual statistical update will certainly take place this evening and we can expect further announcements from the prime minister in the coming days, as the Omicron situation develops.