The leader of Nottingham City Council has emphasised it is a dangerous time for the city after a "dramatic rise" in positive cases of coronavirus.
The city looks set to be given tighter restrictions by Friday this week, and residents are being urged not to visit anyone outside their household in an attempt to lower the rate of infection.
There has been 1,465 positive cases in the city in the seven days leading up to October 3.
David Mellen, the leader of Nottingham City Council, says the city is entering a crucial period - and the rise in the number of cases currently being recorded simply cannot continue.
He told Nottinghamshire Live: "We expect the cases might go up further before they start to fall again. If more people are testing positive, the important thing is to encourage them to self-isolate and help us to stem the rate of infection.
"It can't keep increasing at the rate it is doing. It's a dangerous time for the city and we are all potentially at risk."
Nottingham City Council has had to react quickly, given Nottingham had a significantly lower infection rate just seven days ago, when it stood at 71.2 per 100,000 people.
But the infection rate is now 440.1, meaning the message to the public is to start restricting social contact immediately to try and bring it back down again.
"Please stay with us on this one - this virus is still very much here," Cllr Mellen said.
"People need to keep doing the simple things - wearing your mask, keeping your distance - that we have probably grown a bit bored of. We need to keep doing these things. Please take symptoms seriously and get a test if you need one.
"We are asking people not to mix with other households and keep to the people in your bubble. I understand people can feel very isolated in times like these, but we need to do what is necessary."
He added: "This is not something to be played with - this is very serious.
"240 people have died in this city, a lot of other people have had their lives significantly changed. I have got two brothers who have had the Covid virus and they have certainly been affected by it.
"One of my brothers has had to give up his job - he's not an old man, he's younger than me, but he is still having symptoms months on."
Nottingham's infection rate is currently the fifth worst in the country, behind Newcastle Upon Tyne, Liverpool, Knowsley and Manchester.
Director of Public Health for the city Alison Challenger has said restrictions for the city are "inevitable" and has reiterated the public should not wait for an announcement from the government before following tougher measures.
