People in Dudley have been asked to voluntarily stop mixing with other households.
It comes after a worrying rise in the number of positive coronavirus infections – the rate doubles every two weeks.
The leader of Dudley Council and the director of public health have said there is evidence that the virus is commonly being transmitted in households.
This means residents should avoid meeting others outside their household or bubble in homes and gardens.
People can still go to shops, restaurants, pubs or other venues in a maximum group of six from more than one household, as these places have more Covid-19 secure measures in place.
Councillor Patrick Harley, leader of Dudley Council, said: “We are once again having to come to the people of Dudley and ask them to play their part in helping to protect our communities as rates continue to rise in our borough in line with what we are seeing across the country.
“Today, with a heavy heart, we are asking all our residents to stop meeting in homes and gardens wherever possible as evidence shows this method of social contact could have increased transmission risks.
“We recognise that this is another huge sacrifice for many people in our borough, who have already done so much to help us protect our communities, but we must do all we can to protect ourselves and our loved ones.
“We must not be complacent and need to stay alert as the stark reality is that we could be less than a week away from joining neighbouring areas with further restrictions.”
Dudley is currently classified in the lowest tier – level one or medium risk. Current restrictions for this tier include the rule of six, applying indoors and outdoors, and pubs, bars and restaurants must close at 10pm.
Although Dudley continues to have the lowest rates of coronavirus in the Black Country, figures continue to rise, doubling every two weeks, and there is concern that increased formal restrictions could be placed on the borough within the next week.
Bal Kaur, acting director of public health, said: “Coronavirus cases are continuing to rise across the country, as is the case here in Dudley borough, so we need to act now to slow the spread.
“There is strong evidence that people visiting other households is a common source of transmission and that is why we are asking people to avoid visiting one another’s homes unless it is absolutely essential.
“People should now avoid visiting other households, wash hands regularly, keep a safe distance from others, limit contact with others wherever possible and wear a face covering. Anyone who has symptoms must self-isolate and get tested.”