Boris Johnson is due to set out a plan on Monday for how England will exit its third lockdown.
The prime minister has said he wants the lifting of restrictions to be “cautious but irreversible”.
He is expected to reveal a series of target dates by which the government wants to reopen different sections of society.
Schools are expected to be first on the list, potentially returning as soon as March 8, followed by non-essential retail and then hospitality venues such as pubs and restaurants.
Downing Street has said there are six criteria it will be looking at this week when deciding how and when to lift lockdown.
Infection rates
Johnson has said he wants there to be a “very low” infection rate before restrictions are lifted.
On Monday 9,765 new cases of Covid were reported in the UK, marking the first time the figure had fallen below 10,000 since October 2. For context, on January 8, the number of new cases was 68,053.
The prime minister has not put a numerical figure on how many new infections is too many.
But The Daily Telegraph has reported pushing the infection rate below 1,000 a day will be key to any easing of rules. The last time the infection rate was regularly below 1,000 a day was in August.
Jeremy Hunt, the former Conservative health secretary who now chairs the Commons health committee, has also previously suggested infections might need to be below 1,000 a day before restrictions are entirely lifted.
Number of people in hospital
The latest figures show there were 20,929 people in hospital with Covid on Sunday, the first time it has dropped below the peak of the first wave (21,687 on April 12) and just over half the 39,241 inpatients on January 18.
But when the second lockdown ended at the start of November, there were 13,102 patients in hospital. And when the first lockdown ended on July 4, there were 2,801 – so we may still have a way to go.
Deaths
The UK recorded 799 deaths within 24 hours of a positive test on Tuesday, a fall of nearly 25% compared to the Tuesday before – but still extremely high, as is the seven-day average of 621. The highest daily number of deaths reported was 1,820, on January 20.
Just as with the infection rate, the government has not set a figure it wants to reach before lifting restrictions.
But David Spiegelhalter, a leading statistician at Cambridge University, told Times Radio on Tuesday the UK could see death rates back to “normal” by March. “We’re coming down actually remarkably fast,” he said.
The UK was, by contrast, recording an average 309 deaths a day when the second lockdown lifted in November, and 43 when Britain opened up in July.
The R rate
The reproduction number, or R rate, of coronavirus transmission across the UK is now below 1 for the first time since July.
According the Government Science Office it is estimated to be between 0.7 and 0.9.
R measures the number of people, on average, that each sick person will infect. If R is greater than 1, the epidemic is generally seen to be growing; if R is less than 1 the epidemic is shrinking.
The impact of the vaccination
Crucial to the lifting of lockdown is the vaccination programme. The government is looking at not just what percentage of the population have been vaccinated and given protection themselves, but whether people who have been vaccinated are actually less likely to carry and transmit the virus.
Nadhim Zahawi, the vaccines minister, said on Tuesday the preliminary evidence on the effect of vaccines on transmission was “really encouraging”.
“We have a couple of very large-scale studies related to giving us better data on the vaccines,” he told BBC Radio 4’s Today programme. “We should be able to see really good data in the next few weeks from those studies.”
But Zahawi also warned it was currently unclear how much of the reduction in infections being seen is down to lockdown restrictions or the vaccine rollout.
The government has set itself a target of offering the vaccine to all over-50s and those in at-risk groups, by the end of April.
Prevalence of new coronavirus variants
One area of concern is whether new variants of coronavirus could derail the lifting of restrictions by proving to be more infectious or more resistant to vaccines. It is one reason why the government has decided the infection rate is a key metric.
Johnson has warned: “If you’ve got loads of people, even young people, getting the disease then a couple of things happen.
“First of all, you have a higher risk of new variants and mutations within the population where the disease is circulating. Secondly, there will also be a greater risk of the disease spreading out into the older groups again.”
So while Johnson has said he wants the lifting of England’s third lockdown to be “irreversible” it remains unclear how long it will take. The prime minister also notably has not ruled out imposing a fourth. “No, I can’t give that guarantee, of course not,” he told a Downing Street press conference on Monday. “Because we’re battling with nature, with a disease that is capable of mutating and changing.”