Britain's Johnson urges people to follow guidance after 281 deaths

British Prime Minister Boris Johnson warned on Sunday that if British citizens did not more strictly adhere to social distancing, then further government measures could be introduced.

His remarks followed a sunny weekend in the U.K., with social media filled with pictures of packed parks and public spaces.

The U.K. Department of Health announced on Sunday that the death toll from coronavirus is 281, an increase of 48 in 24 hours. The total number of positive cases now stands at 5,683 in the country.

"I want, of course I do, people to go to the parks and open spaces and enjoy themselves," Johnson said.

"Please follow the advice and don't think fresh air ... automatically provides immunity," he told a press conference.

Johnson warned those who thought they were "invulnerable" that they could nevertheless spread the disease to others.

He said that as things stand the "health benefits of keeping parks open outweigh epidemiological value of closing them."

"If people don't exercise responsibly in the parks and green spaces, there is going to be no doubt we are going to bring forward further measures and we are keeping that under constant review," he warned.

The prime minister spoke alongside Secretary for Housing, Communities, and Local Government Robert Jenrick and Deputy Chief Medical Officer for England Dr. Jenny Harries.

Harries said: "People who currently are congregating, they are dangerous … They are making the outside environment unavailable to others who need it."

Jenrick said: "The National Health Service has identified up to 1.5 million people in England who face the highest risk of being hospitalised by the virus."

He announced that the National Health Service would shortly be in touch and ask them not to leave their homes for 12 weeks. Other members of the household could still leave the house, but must follow social distancing rules; carers could also visit these households.

The government will set up local hubs to distribute food and medicine to these vulnerable people, with parcels left on the doorstep. Both emergency service and the armed forces have been drafted in order to support the effort.

London

The British capital has been ahead of the wider U.K. trend of increased coronavirus cases.

Today's press conference focusing on social distancing was in large part aimed at London.

Earlier in the day, London Mayor Sadiq Khan told BBC: "My message to all your viewers is simple: Life has changed, we've got to do things differently for a while now."

"Social interaction leads to the disease spreading, leads to people dying. Don't leave your home unless you really, really have to," he said.

On police enforcement of social distancing and locking down of the city, Khan said: "It's really important that the police are focused on the priorities that they've got, dealing with violent crime and other issues, but clearly, if it is the case that people continue to act in a way that's leading to this disease spreading, then those sorts of things will have to be considered."

Mother's Day

In a bleak Mother's Day message, Johnson said: "I know that everyone's strongest instinct is to go and see their mothers in person, to have a meal together, to show them how much you love them.

"But I am afraid that this Mothering Sunday the single best present that we can give -- we who owe our mothers so much -- is to spare them the risk of catching a very dangerous disease. The sad news is that means staying away.

"This time the best thing is to ring her, video call her, Skype her, but to avoid any unnecessary physical contact or proximity. And why?

"Because if your mother is elderly or vulnerable, then I am afraid all the statistics show that she is much more likely to die from coronavirus, or COVID-19. We cannot disguise or sugar coat the threat."

On coronavirus, he said: "The numbers are very stark, and they are accelerating."

Johnson referred to the situation in Italy in order to underscore the point: "The Italian death toll is already in the thousands and climbing. Unless we act together, unless we make the heroic and collective national effort to slow the spread, then it is all too likely that our own National Health Service will be similarly overwhelmed."

The virus, which emerged in Wuhan, China last December, has spread to at least 169 countries and regions around the globe, while the tally of confirmed cases has topped 322,000, according to data compiled by U.S.-based Johns Hopkins University.

The global death toll is over 13,700, causing a chain reaction as governments placing countries on lockdown to stem the spread.

Despite the rising number of cases, a vast majority of people contracting the virus suffer mild symptoms before making a recovery.

So far, some 95,000 people have recovered from the disease.