Scientists have urged people to rethink Christmas as coronavirus infection rates increase in parts of the UK, warning the country is heading towards "disaster".
Just because people can meet up, it does not mean they should, according to Independent Sage.
The group, chaired by former Government chief scientific adviser Sir David King, said there is a need to highlight the risks of mixing indoors.
Families who decide to meet up over the five days that Covid-19 restrictions are relaxed over the festive period must be advised on how to keep their homes safe, the experts said.
Independent Sage is also calling for a pandemic fuel allowance so people can keep their homes ventilated while at the same time turning up the heating to stay warm.
Professor Stephen Reicher, of the University of St Andrews, said: "Right now we are heading towards disaster.
"Given high levels of infection across the country and the increasing levels in some areas (such as London) it is inevitable that if we all do choose to meet up over Christmas then we will pay the price in the New Year."
He added: "We need an urgent rethink about the Christmas break.
"Government must clarify the risks involved in indoor mixing and stress the fact that households can get together doesn't mean that they should.
"They should provide the information and support to help people make the decisions that best keep themselves, their families and their communities safe.
"And for many of us, the right decision will be to show our love by waiting until we can meet and hug and celebrate without danger."
Prof Reicher warned: "I think there needs to be a very clear argument that while you might make that choice, you need to think very, very carefully about what's the best thing to do at this point in time – the safest thing, by far, is not to mix.
"The best way to keep your family and your community safe is to delay things into the new year, when things are safe.
"And it would be particularly tragic if relatives get infected, and if relatives die at the point when a vaccine is on the horizon."
The UK Government and devolved administrations have agreed a joint plan to relax social distancing rules over the festive period, allowing friends and family to hug for the first time in months.
In England three households will be able to mix from December 23 to 27.
Each Christmas bubble can meet at home, at a place of worship or an outdoor public location, but existing, more restrictive rules on hospitality and other venues will be maintained throughout the period.