NHS bosses have urged the Government not to drop any Tier 3 areas to 2 today - as officials were locked in crunch late-night talks.
Millions in England face an agonising wait to be discover whether they will be plunged into the toughest restrictions this morning.
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It comes as Boris Johnson was last night warned there would be riots if he forced cities with low Covid rates to remain in Tier 3.
Health chiefs are putting pressure on the Government not to loosen laws for any Tier 3 areas - including those where cases have dropped.
NHS Providers, which represents the 216 NHS acute, ambulance, community and mental health trusts in England, has written to Mr Johnson warning of a third wave.
Urging "extreme caution" on moving areas down a tier, organisation officials said: "Trust leaders are worried that if infection rates remain as high as they are the moment, relaxing the restrictions will trigger a third wave."
'EXTREME CAUTION'
Greater Manchester and Leeds have been hammering at No10’s door to go down into Tier 2 after their infection rates fell below the national average.
Coventry, Warwickshire and Solihull are also clamouring to be freed from the harshest rules after their rates fell since the last decision.
One political insider in the Midlands told The Sun: “If they don’t come out of Tier 3 there will be riots.
"They have brought their rates down immeasurably, there is no reason for them not to come out.”
But a Whitehall insider told The Sun: “I would be surprised if any area goes down a tier.
ENDS IN TIERS
Despite that, a source told The Sun: “I would be surprised if any area goes down a tier.
“It would look very strange to loosen restrictions when everyone is so worried that the Christmas rules could fuel higher rates.”
The review, chaired by Health Secretary Matt Hancock, began late last night and the decisions will be reported to Parliament today.
Any changes will take effect from Saturday and comes as UK Covid cases continue to rise.
Politicians' decision on the tier system takes place just hours after London and much of the South East went into Tier 3 amid rocketing Covid rates.
Pubs, restaurants and theatres have all been shut down across the capital and its neighbouring regions.
There are now around 34million people in England living under the toughest rules.
Downing Street is expected to take a hyper cautious approach as they battle to dampen down Covid infection rates before the Christmas lockdown amnesty.
The PM yesterday announced a series of five strict rules ahead of relaxing restrictions for the festive season - including that people must quarantine for five days before seeing loved ones.
People over the age of 70 have been asked to skip meeting friends and family altogether.
Public Health England (PHE) data showed that more than two-thirds of areas across England are seeing a rise in Covid-19 case rates.
According to data from the ZOE Covid Symptom Study App, run by researchers at King's College London, Oxfordshire, East and West Sussex, Brighton and Hove and Northamptonshire have all seen an uptick in infections.
Oxfordshire is currently in Tier 2 and data from the app shows that the area has 188 cases per 100,000 and 50 cases per 100,000 people in the over 60s.
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Data from PHE states that seven days ago, 126 out of a total of 315 local authority areas had recorded a week-on-week jump in rates. That figure now stands at 222.
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It was also announced today that councils in worst-hit Tier 2 areas will be offered community testing - just like Tier 3 regions.
Matt Hancock said: "The sooner we get this virus under control, the sooner we can ease these restrictions and get back to doing the things we love.”