Mixing at Christmas poses “substantial risks”, particularly for older people, and there is “far too much emphasis” on having a normal festive period, a Government scientific adviser has said.

Andrew Hayward, professor of infectious disease epidemiology at University College London (UCL) and a member of the Scientific Advisory Group for Emergencies (Sage), said the country was “on the cusp” of being able to vaccinate older populations and it would be “tragic” to throw away the gains made in suppressing coronavirus.

He also attacked the Government for “inconsistent” messages over what to do, saying it was clear that if people wanted to avoid Covid-19 they should not mix indoors.

His intervention came ahead of the Government reporting a further 501 people had died within 28 days of testing positive for Covid-19 as of Thursday, bringing the UK death total to 53,775, while there have also been a further 22,915 lab-confirmed cases of coronavirus in the UK.

Elsewhere Scotland’s First Minister Nicola Sturgeon told MSPs the chief medical officers of all four UK nations have been asked to draw up plans for easing some restrictions and a “concrete” plan could be revealed as early as next week.

And a leading World Health Organisation (WHO) official suggested families could meet for picnics in the park during the festive season as he said this year will be “a different Christmas but that does not mean it cannot be a merry one”.

Speaking in a personal capacity, Prof Hayward told BBC Radio 4’s Today programme: “Mixing at Christmas does pose substantial risks, particularly in terms of bringing together generations with high incidence of infection with the older generations who currently have much lower levels of infection and are at most risk of dying if they catch Covid.

“My personal view is we’re putting far too much emphasis on having a near-normal Christmas.

“We know respiratory infections peak in January so throwing fuel on the fire over Christmas can only contribute to this.”

Asked if people should worry more about the health and welfare of their parents and grandparents than gathering together for a movie over Christmas, Prof Andrew Hayward from UCL replied: “Well exactly.

“We’re on the cusp of being able to protect those elderly people who we love through vaccination and it would be tragic to throw that opportunity away and waste the gains we’ve made during lockdown by trying to return to normality over the holidays.”

Prof Hayward said he believed “there is a cost” to gathering families together, adding: “When policies are undulating between stay at home to save lives, eat out to help out, the tier system, second lockdown and proposals for an amnesty on social distancing, it’s a highly inconsistent message.

“Whereas in fact the things that people need to do to stay safe and to keep their loved ones safe are relatively simple.

“Avoid, as far as possible, indoor close contact with people outside of your household, avoid crowded places and protect the most vulnerable by not putting them at unnecessary risk.”

The expert said the reproduction number – the R value – of coronavirus still needed to get below 1 for the epidemic to shrink.

“Approaching 1 is not good enough – that still means the infection is increasing,” he said.

“It needs to be clearly below 1 and it needs to get to low levels, rather than the high levels that we still have.”

Asked whether he would impose further restrictions throughout December such as stricter tiers than before lockdown, he said “it is a very difficult balance”.

Downing Street has suggested families should be able to meet up after a “difficult year” and Defence Secretary Ben Wallace said on Thursday a final decision will be made as close to the end of England’s national lockdown as possible.

Reports suggest households might be allowed to mix indoors for a five-day period from Christmas Eve, and that ministers are considering plans to allow three or four households to form bubbles.

However, a five-day easing could mean a potential 25-day period of tighter measures into January if the Government was to follow advice from scientists.

Mr Wallace told ITV’s Good Morning Britain: “I don’t want to be the Grinch that stole Christmas – I’m not campaigning for that.

“I would love all of us to be able to have a Christmas, but more than anything I want us to get through this Covid and try and get this country back to normal and I want to protect lives.”

Dr Hans Kluge, WHO regional director for Europe, pointed out many marked other religious festivals, including the Islamic holy month of Ramadan and the Hindu festival Diwali, with virtual gatherings and “distance celebrations”.

He said; “If it’s a large gathering of vulnerable people, you may postpone that gathering until you can safely gather.

“Despite the cold, if local restrictions permit, gather outside with loved ones for picnics in the park.”

It comes as Oxford University published phase 2 results from its clinical trial into a coronavirus vaccine, showing it produces a strong immune response in older age groups.

Professor Andrew Pollard, head of Oxford’s vaccine trial team, said he was “absolutely delighted” with the results and the jab was “well tolerated” in older people.