Britain's top medical advisers on Monday painted a grim picture of exponential growth in illness and death if nothing is done to control the second wave of coronavirus infections, laying the groundwork for the government to announce new restrictions later this week.
"At the moment, we think the epidemic is doubling roughly every seven days", Sir Patrick said at the briefing held at Downing Street.
The challenge now, he added, is to prolong the time it takes for infection rates to double.
But new Covid-19 cases are rising by at least 6,000 per day in Britain, according to week-old data, hospital admissions are doubling every eight days, and the testing system is buckling.
He warned the "50,000 cases per day would be expected to lead a month later, so the middle of November, say, to 200-plus deaths per day".
Mr Hancock said he wanted Christmas to be "as normal as possible" and suggested a vaccine could be available early next year "if all goes well".
"We all know we can not do this without some significant downsides". "Last week, the government limited gatherings to no more than six people, indoors or out".
Ministers were reported to be split on how far any new restrictions should go.
In one week, anyone who has coronavirus symptoms or is otherwise asked to self-isolate will be legally required to do so - or face fines that start at 1,000 pounds (about $1,280).
There were no new measures announced today, though some expect harsher restrictions on households mixing to be enforced soon.
Coronavirus cases in the United Kingdom are rising exponentially and chief medical officers are urging the Government to raise the covid alert level from level 3 to 4. It has risen sharply in recent weeks.
Vallance said efforts to find a vaccine are continuing and while it is still not clear they will work, t here is increasing evidence the research is pointing in the right direction. "We see an increase in positivity of the tests done - so we see the proportion of people testing positive has increased, even if testing stays flat".
Nearly 42,000 people who have tested positive for Covid-19 have died in Britain, the worst death toll from the pandemic in Europe.
Sir Patrick said: "What we see is that something under 8% of the population have been infected as we measure the antibodies".
They predict the United Kingdom could see up to 50,000 cases per day by mid-October if no action is taken, reminding people there is "no evidence" to suggest a milder strain of the virus was in circulation.
"It means the vast majority of us are not protected in any way and are susceptible to this disease".
Referring to outbreaks in Spain and France, Vallance said, "It started with younger people in their 20s and spread gradually to older ages, as well".
The rise in cases could lead to an eventual rise in hospitalisations, which will inevitably lead to a rise in deaths.
"This disease spreads by droplets, by surface contact and by aerosols", Vallance said.
He urged everyone in the U.K.to be mindful of preventing the virus from spreading.