The rise of the Delta variant – formerly known as the Indian variant – has to leaders issuing the plea for residents to take extra care.
It comes as fears continue to grow over whether the variant could lead to a third wave – and delay the easing of restrictions on June 21.
Councillor Jasbir Jaspal, Wolverhampton Council's cabinet member for public health and wellbeing, said: "Despite everyone's best efforts, Covid-19 hasn't gone away and unfortunately we are now seeing evidence that it is starting to make a resurgence in some parts of the country.
"It's really important that we avoid a third wave by stopping this deadly virus in its tracks and preventing the Delta variant from taking hold here in Wolverhampton."
Councillor Jaspal urged people to continue to follow the guidance, get themselves tested and take up the vaccine if they're eligible. She added: "Although the rise in new cases is a concern, we should be reassured by the progress we have made over recent weeks and months – and that by doing all we can to prevent the spread of Covid-19 we will see the back of this virus in due course."