A loosening of restrictions on household mixing over Christmas would lead to further deaths, a top scientist has warned. 

Professor Neil Ferguson, whose modelling led to the original lockdown in March, told BBC Radio 4′s Today programme on Saturday that decisions on whether or not to dial back the rules for festive celebrations amounted to a “political judgment”.

He said: “It risks some transmission and there will be consequences of that. Some people will die because of getting infected on that day.

“But if it is only one or two days the impact is likely to be limited. So that is really a political judgment about the cost versus the benefits.”

His warning follows comments made by a government scientific adviser on Friday that the idea “we can carry on as we are” and have a normal Christmas “is wishful thinking in the extreme”. 

Professor John Edmunds, a member of the Scientific Advisory Group for Emergencies (Sage), said “radical action” would be needed to stem the rise in coronavirus cases, particularly in regions with high incidence of the virus.

Downing Street has previously said it is the government’s “ambition to ensure that people may celebrate Christmas as a family this year”.

Ferguson also warned during the interview that the NHS will be unable to cope in a month’s time if coronavirus cases continue to increase at the present rate.

He explained that while infections among 18 to 21-year-olds were falling, they were continuing to rise in other age groups.

“Unfortunately, in every other age group case numbers continue to rise at about the same rate they were. There are little hints of slowing, for instance in the North East of England, but we are not seeing the sort of slowing that we really need to to get on top of this,” he told the BBC Radio 4 Today programme.

“It is a worrying situation. We now have 8,000 people in hospital with Covid. That is about a third of the level we were at the peak of the pandemic in March.

“If the rate of growth continues as it is, it means that in a month’s time we will above that peak level in March and that is probably unsustainable.

“We are in a critical time right now. The health system will not be able to cope with this rate of growth for much longer.”

The top scientist also suggested that schools may have to close to older pupils – who appear more capable of spreading the virus than younger children – in order to reduce the rate of transmission. 

Ferguson warned that if restrictions on households mixing fail to stem the rise of coronavirus infections the government may have to take action in education settings. 

“That [banning households mixing] should have a significant effect but as yet we have been unable to see it definitively,” he said. 

“If we go beyond that there is a limit to what we can do in terms of reducing contacts, short of starting to target, for instance, the older years in schools and sixth form colleges where we know older teenagers are able to transmit as adults.

“Of course nobody wants to start moving to virtual education and closing schools even partially. The challenge may be that we are not able to get on top of the transmission otherwise.”