Covid-19 infection rates are the highest they've ever been in England, raising serious concerns about the country's response to the virus.
A nationwide study found that case rates almost doubled in England from September to October this year, hitting 1.72% of the population infected between October 19 to October 29.
That means one in every 58 people had the bug during that period.
Some areas were even worse hit, with the rate reaching one in every 42 people in the South West.
The virus continues to rip through schools, the React-1 study found, infecting 5.85% of five to 12-year-olds, and 5.75% of 13 to 17-year-olds.
In January this year, after the Delta variant took hold and the country was plunged into a strict lockdown, the prevalence was estimated to be 1.57%.
Paul Elliott, director of the React programme at Imperial College London, said that the spike in cases among young people coincided with half-term.
"We do know that we saw a very, very similar pattern in round six at the same time last year, where over the half-term period the rates dropped," he said.
"And then actually they rebounded and went up again. So I think watching what happens in the next week, 10 days, is going to be really critical."
The alarming figures come as the Prime Minister continues to insist that no further measures to limit transmission are needed.
Asked if he could guarantee a good Christmas at the end of last week, Boris Johnson said: "I see no evidence whatever to think that any kind of lockdown is on the cards."
The option to instigate Plan B - which would see a return of mandatory face mask wearing and working from home, among other measures - remains available to the government.
Mr Johnson's optimism is at odds with the outlook of Professor Johnathan Van-Tam.
England's deputy chief medical officer warned that Covid is "running too hot" and that there are difficult months ahead.
"The rates are still very high at the moment," Professor Van-Tam told BBC Breakfast and BBC Radio 5 Live.
"They are higher than in most of Europe. And we are running quite hot - I think that's the right expression.
"And, of course, it's of concern to scientists that we are running this hot this early in the autumn season.
"And so, from that perspective, I'm afraid it's caution, followed by caution, and we need to watch these data very carefully indeed over the next days and weeks."
Britain has about 40,000 daily cases of Covid, according to the latest seven-day average.
That total is second only to the roughly 74,000 a day in the United States, which has five times more people.
Ten worst hit local areas in England
- Cheltenham
- Stroud
- Swindon
- Gloucester
- Cotswold
- South Gloucestershire
- Wiltshire
- Tewkesbury
- Bath
- North East Somerset and City of Bristol
Coronavirus prevalence per person
- South East: 1.84% from 0.57%
- North East: 1.96% from 0.84%
- North West: 1.83% from 099%
- Yorkshire and the Humber: 1.54% from 1.25%
- East Midlands: 1.69% from 1.15%
- West Midlands: 1.67% from 1.01%
- East of England: 1.62% from 0.73%
- London: 1.31% from 0.62%
- South West: 2.18% from 059%
While the vaccine has weakened the link between Covid cases and deaths, 131 people died across the UK each day of the last week on average, while more than 9,500 coronavirus patients are currently receiving treatment in hospital.
The startling high figures have left already beleaguered hospital staff feeling anxious and exhausted as the winter period approaches.
Intensive care nurse Dave Carr said: "We are dead on our feet physically. We are dead on our feet mentally.
"I don't know how to get out of this mess. I can't walk away because of the guilt of leaving my colleagues."
Chaand Nagpaul, chair of the British Medical Association, is one of many medical professionals calling for the government to act to ease pressure on the NHS.
"We do not understand why the government has removed mandatory mask wearing in transport and in indoor settings like shops because that doesn't actually stop the economy functioning – but it would reduce infection," he said.
"The government clearly believe these simple measures do make a difference, yet they're failing to act by not making these a requirement.
"Without other preventative measures put in place now, the challenges coming our way could go from being achievable to totally insurmountable."
It is hoped that the high Covid rates experienced at the end of October will begin to ease as more children take the vaccine.
Data suggests the uptake has been slow so far.
Helen Ward, professor of public health at Imperial College London, said: "We know that vaccination uptake in children, the 12-plus-year-olds, is not very high and that's where we've got most infection.
"And then there's the question as yet undecided as to whether or not even younger children might be vaccinated.
"Children are one group where it is continuing to circulate and therefore with (the) return to school following half-term you would expect there to be more transmission going on there.
"And the parents of those children are the other age group that we saw higher increases in, and are also the age group that are not yet eligible for booster doses.
"And so if there is significant waning in the effectiveness of the vaccine after four or five months, that would overlap with that age group.
"So that is why it's really important to continue monitoring what's happening in both the whole population but particularly those age groups that may become vulnerable again."
Around 10% of the positive samples examined in the React-1 study were a mutation of the Delta variant - AY.4.2 - and officials have said they are monitoring the spread of the so-called "variant under investigation".
Commenting on the study, Dr Jenny Harries, chief executive of the UK Health Security Agency, said: "Although the number of hospitalisations and deaths remain lower than in previous peaks, these findings are a powerful reminder that the pandemic is far from over and remains a serious threat to health and wellbeing.
"This new data strongly reinforces the need for all eligible age groups to get vaccinated and to take mitigating measures such as wearing a face covering in crowded places and ensuring good ventilation indoors.
"This is particularly urgent for older people whose immunity may be waning given that several months have passed since they received their jabs.
"I strongly encourage everyone who is eligible for a third dose or a booster shot to come forward without delay."
Health and Social Care Secretary Sajid Javid said: "Today's report sends an important message that we need to stay vigilant as we head into the winter months.
"Vaccines continue to be our first line of defence against this disease and it is crucial we all get jabbed to keep the virus at bay."
