Young people in Preston are being targeted with a "Don't kill Granny" message to slow the spread of coronavirus after the area had lockdown restrictions imposed.
Households mixing in pubs and homes has been blamed for a rise in cases in the city, but locals suggest the restrictions will not be taken seriously and pubs were said to be busy on Friday night despite the Government's intervention just hours earlier.
The Department of Health and Social Care (DHSC) announced on Friday that households in the city will be banned from mixing indoors or in gardens.
It comes a week after the same measures were brought in for residents in Greater Manchester, parts of east Lancashire and West Yorkshire, as well as Leicester.
The rules will remain in place for those areas for at least another week.
Officials said there had been a "significant" rise in cases in the under-30 age group in the Preston area.
Director of public health for Lancashire Sakthi Karunanithi said the "two main reasons" for the rise in infections were people meeting others in their homes, and households coming together in venues such as pubs.
"These two are key behaviours we're trying to protect people from. Don't meet with members of other households in pubs and clubs," he said.
Preston City Council chief executive Adrian Phillips told BBC Radio 4's Today programme: "I know our director of public health has said 'Don't kill Granny' to young people to try and focus the message.
"Young people are inevitably among the brave and the bold, they want to be adventurous and out and about, but we know that they have the virus, are more likely to at the moment, they often have less symptoms but they do take it back to their household and the community spread we are seeing, we believe, in many cases are young people taking it home and catching the virus."
He also backed the Local Government Association's call for councils to have greater powers to close pubs to slow the spread of Covid-19.
"You need responsive powers," he said. "It is useful to have something that can move quickly and we can make it entirely clear to the licensee or the operator what the consequences are."
On Saturday morning, Charlene Gardner, 38, was in Preston city centre to buy school shoes for her two children.
She said: "I was happy the restrictions were brought in because I think we do need the police to get involved.
"The pubs around us were still 30 or 40 deep outside last night.
"It won't mean any changes for us because we haven't been seeing family anyway but I saw some reaction online last night and I think a lot of people aren't going to listen to it."
Many people in the Fishergate shopping street were wearing masks, and one man with a stand selling face masks, who did not want to be named, said the city was less busy than the previous weekend.
But he said he did not think people were taking restrictions seriously.
He said: "You see the older people wearing masks but the younger ones don't.
"The problem is in the pubs and they don't wear masks there."
There were 61 new cases in Preston in the seven days to August 4, which is the equivalent of 42.6 cases per 100,000 people – up from 21.7 per 100,000 in the previous seven days.
The Government said guidance will make clear that people should not be gathering with other households anywhere indoors.
The restrictions on gatherings will be reviewed again next week, with any changes to be announced by August 14.
Preston's new restrictions came into force at midnight and mean residents cannot have other people in their homes and gardens, cannot visit others' homes or gardens, even if they are in an unaffected area, and are not permitted to mix with other households in indoor venues.
Social bubbles are exempt from the restrictions, and residents can meet in groups of up to six – or more than six if exclusively from two households – in outdoor areas such as parks and beer gardens.
Households can also visit indoor hospitality venues, as long as they do not mix with others.