Lincolnshire will move to tier 4 from December 31, but North and North East Lincolnshire will remain in tier 3.
This comes as a record daily number of cases were recorded across the UK on Tuesday (53,135) and over 21,000 people are in hospitals with COVID-19.
Some three quarters of the UK population will now be placed in tier 4, with almost all areas in tiers 3 or 4.
This includes the City of Lincoln, Boston, South Kesteven, West Lindsey, North Kesteven, South Holland and East Lindsey.
Neighbouring counties Leicestershire, Nottinghamshire, Derbyshire, Northamptonshire will also move into tier 4.
Similar to the November national lockdown, in tier 4 all non-essential shops must close, travel is not advised and socialising is banned. Full tier 4 government guidance here.
Cllr Martin Hill, Leader of Lincolnshire County Council said: “Despite infection rates coming down in Lincolnshire, the government has decided tier 4 restrictions are needed here.
“We realise this will be difficult news for some, particularly those shops and businesses that will have to close, and we’ll continue to press for them to receive the necessary support.
“However, we can’t ignore the increasing pressure on hospitals, and I urge everyone to stick to the new restrictions.
“Keep to the hands, face, space guidelines, and, if you develop any symptoms, no matter how mild, then please self-isolate and get tested.
“Today’s approval of the new vaccine means we can now see the light at the end of the tunnel. However, let’s not be complacent and let things slip, as we aren’t out of the woods yet.”
Here’s what you need to know about tier 4:
Katrina Pierce, Development Manager for the Federation of Small Businesses in Lincolnshire said the news is “devastating for small businesses”.
She added: “Entering a new year under the toughest restrictions after a turbulent 2020 will not only further knock morale among business owners, it will hit their accounts too.”
Health Secretary, Matt Hancock said: “I know that tier 3 and 4 measures place a significant burden on people, and especially on businesses affected, but I’m afraid it’s absolutely necessary because of the number of cases that we’ve seen, but where we’re still able to give places greater freedoms we will continue to do so.”