Residents and businesses in Middlesbrough are being urged to strictly follow coronavirus guidelines as investigations into an increase in cases continue.
Middlesbrough Council is now aware of 48 positive cases of interest, dating back to July 31.
The Council first alerted the public to a cluster of positive tests a week ago.
Several of those cases were linked to a small number of households and families in the Acklam and Linthorpe areas. Contact tracing is now under way on a small number of cases linked to homes in the town centre.
The Council is stressing the urgency of following the rules around social gatherings and mixing with other households.
No more than two households can mix together indoors and no more than six people from different households can mix together outdoors. It is against the law for more than 30 people to gather in a private house or garden.
The public are also reminded to wear face coverings in shared vehicles, including taxis, and when in other enclosed public places like shops.
Mayor Andy Preston said: "Our teams acted swiftly to respond to the spike but we've got to be so careful. Every single person and business can help keep people healthy and save jobs by doing the right things.
"Wash your hands regularly - as often as you did back in March - wear a face covering and get a test even if you have only have mild symptoms. We can test hundreds of people a day in Middlesbrough.
"No one should panic, but please let's use the past week as a reminder of how damaging Covid can still be to lives and jobs in Middlesbrough."
South Tees Joint Director of Public Health Mark Adams said: "Recent cases remind us all how quickly the virus can spread.
"People from a wide age range have tested positive and this is a warning to everyone.
"Limiting your contact with other people remains vital. Put simply, the more contact you have with those outside your household, the more likely you are to be infected."
The Council is working with Public Health England's North East Health Protection Team to contact trace the recent cases.
Close monitoring of new cases will continue and anyone with even mild coronavirus symptoms is urged to book a test online or by calling 119.
The symptoms of coronavirus are a high temperature, a new, continuous cough or a loss or change of sense of taste or smell.
Testing in Middlesbrough
There is capacity for more than 1,000 tests on any one day in Middlesbrough with the regional testing site at the unused Sainsbury's near the Riverside Stadium open from 8am until 8pm every day.
Additionally, the mobile testing unit now based at Newport Community Hub (St Paul's Road, TS1 5NQ) will remain at the site until August 21.
The centre's opening times for Saturday August 15 have been amended to 1pm - 5.30pm.
The centre is operated on behalf of the Department of Health & Social Care and has been deployed in response to a local increase in cases. The Council has thanked Teesside University for its assistance in hosting the unit last week.
To book a test call 119 or visit this website: https://www.nhs.uk/conditions/coronavirus-covid-19/testing-and-tracing/get-a-test-to-check-if-you-have-coronavirus/
If you arrive at the mobile testing unit without a booking, you will be supported to register so you can be tested.