The government is reportedly considering plans to introduce a two week “circuit breaker” after Christmas to stop the spread of the Omicron variant.
Under the rules people would be banned from meeting other households indoors immediately after Christmas, The Times reports.
Models suggested that these measures could halve a peak of hospital admissions that might otherwise break the NHS.
Government advisers have warned that tougher measures need to be imposed “very soon” to stop hospital admissions reaching 3,000 a day amid.
This includes measures previously seen in step one and two of the easing of lockdown restrictions such as a ban on indoor mixing and indoor hospitality, the BBC reports.
Scientists also warned against delaying interventions until 2022.
During the Sage meeting, advisers warned: “The timing of such measures is crucial. Delaying until 2022 would greatly reduce the effectiveness of such interventions and make it less likely that these would prevent considerable pressure on health and care settings.”
The Financial Times claims Boris Johnson has been presented with a number of options under a so-called Plan C, which could range from “mild guidance to nudge people, right through to lockdown”.
The paper quotes allies of the Prime Minister who said he still preferred the guidance route – but that he also has to be realistic about the threat of Omicron.
A Government spokesperson said: “The Government will continue to look closely at all the emerging data and we’ll keep our measures under review as we learn more about this variant.”
A Cobra meeting is set to be held over the weekend with the leaders of Scotland, Wales and Northern Ireland.
Stephen Reicher, professor of social psychology at the University of St Andrews and a member of Sage, has warned that Plan B measures are not enough to stop the spiralling number of cases.
Speaking to Times Radio on Saturday, he said: “The only way really, or at least the most effective way, we can have an immediate effect is to decrease the number of contacts we have.
“In many ways, the most effective way of diminishing contact is to have a circuit-breaker.
“Now, you could have it after Christmas, the problem is after Christmas it’s probably too late, it’s probably by then we will have had a huge surge of infections with all the impact upon society.
“When people say ‘look, we don’t want to close down’, of course, we don’t want to close down. But the problem is at the moment, things are closing down anyway, because of the spread of infection.
“So I think we need to act now.”
Mr Johnson has warned Omicron is a “very serious threat to us now” as infections and hospital admissions continue to surge.
On a visit to a vaccination centre in Hillingdon, west London, on Friday, he said: “We are seeing a considerable wave coming through and people have got to be prepared and they have got to understand what it entails.”
Asked about conflicting messages from the Government and its advisers on socialising over the Christmas break, Mr Johnson said: “What both Chris Whitty and I are saying is that there is a big wave of Omicron coming through.
“People need to be prudent. You need to think about your budget of risk.”
According to the Government’s latest figures, a further 93,045 lab-confirmed Covid-19 cases were recorded in the UK as of 9am on Friday, the highest daily total recorded since the pandemic began and a rise of 4,669 on the previous record set on Thursday.
The number of people in hospital with Covid-19 in London, which has seen some of the biggest rises in cases in the last seven days, has climbed to 1,534, up 28.6% on last week.
The Government’s dashboard showed that 341 more people with Covid were in hospital in the capital on December 17, rising from 1,193 on December 10.
Across the UK, 7,611 people are in hospital with the virus, a rise of 163 patients (2%) on the previous week.