Professor Hayward told BBC Radio 4's Today programme on Thursday: "Mixing at Christmas does pose substantial risks, particularly in terms of bringing together generations with high incidence of infection with the older generations who now have much lower levels of infection and are at most risk of dying if they catch Covid".
Boris Johnson is facing mounting pressure to decide whether to ease lockdown measures over Christmas.
The recent increase in the virus has caused concern among Ministers and officials but it is hoped the spike in cases are linked to people holding parties over Halloween.
'My personal view is we're putting far too much emphasis on having a near-normal Christmas, ' he told Radio 4's Today programme.
But he added: "Christmas is a special time of year and we've had such a hard year in 2020 - it has been such a bad year and having some hope, some joy at Christmas, I know that would be welcomed by so many people".
Downing Street declined to say whether door-to-door carol singing would be allowed but the PM's spokesman said there would be no ban on the sale of mistletoe. Another minister added that restrictions will be in place "for quite a while" and that this will be easier following a "decent" Christmas.
Similar curbs are in force in mainland Scotland, a fresh lockdown will prevent gatherings of more than one household in Northern Ireland from Friday and Wales has rules governing people mixing indoors. An alternative would be to simply relax the Rule of Six to allow larger groups.
A Whitehall source said consideration had been given to lifting restrictions on December 24 but it was feared that would not give businesses enough time to benefit from pre-Christmas footfall. One proposed timetable would run from Christmas Eve to the Bank Holiday on December 28.
He added: "I just think it would be such a boost to the whole of the United Kingdom if the four nations can come together and agree a set of arrangements which are safe, careful and sensible but also allow families to see each other at Christmas".
A warning from Public Health England that each day of festivities would have to be followed by five days of lockdown caused irritation in Whitehall and was downplayed.
The government also reduced their estimate of the reproduction "R" number, and said the daily growth rate had fallen to between 0 per cent and 2 per cent.
One Government adviser yesterday suggested that indoor socialising would have to be banned across England after December 2. This would deal a big blow to the hospitality sector.
"We need to think very seriously about Christmas and how we're going to spend it".
"And that's why I totally agree with your observation that we have to make sure, when we make the decision, we a make it as close to the time as possible so we have all the information to make sure the risk is minimal".
He also said he expected social distancing rules to last in some form until at least next summer.