Britons have been urged to avoid all non-essential travel and social contact including trips to pubs, clubs or theatres and to work from home if possible, in the latest drastic attempts to slow the spread of coronavirus.

Prime Minister Boris Johnson said analysis by the Scientific Advisory Group for Emergencies (Sage) indicates that “we are now approaching the fast growth part of the upward curve” in the number of cases.

The Herald: Camley's cartoon: Britons asked to avoid unnecessary social contact.Camley's cartoon: Britons asked to avoid unnecessary social contact.

“Without drastic action cases could double every five or six days,” he said. From today mass gatherings are something “we are now moving emphatically away from”, he added.

Scotland has already banned events attracting 500 or more people, which would require police and ambulance workers on standby.

England’s chief medical officer, Professor Chris Whitty, said the advice on cutting social contact will be in place for a “minimum of weeks to months”. “Depending how it goes it, it may be longer,” he added.

In the Commons, Matt Hancock, the UK Health Secretary, gave a statement to update MPs, saying the Government’s new measures were unprecedented in peacetime.

“We will fight this virus with everything we’ve got,” he said. “We are in a war against an invisible killer and we’ve got to do everything we can to stop it.”

Scotland is to receive a virus fighting fund of £780 million from the Treasury to ensure health services, businesses and the public have the resources needed to tackle Covid-19. Amid growing fears for the economy, the G7 group of leading industrialised nations vowed yesterday to use the “full powers of our governments” to combat the outbreak.

The leaders of the UK, United States, Germany, France, Italy, Canada and Japan also committed to co-ordinating on measures to protect public health and restore global confidence, as well as examining the use of “monetary and fiscal measures” to support global growth, confidence and stability.

It came as the number of confirmed cases in the UK rose to 1,543, including 171 in Scotland, with the death of a 68-year-old from Wales taking the total number of fatalities to 55.

Mr Johnson said anyone living in a household with somebody who has either a persistent cough or fever must now also isolate themselves for 14 days.

“That means that if possible you should not go out, even to buy food or essentials, other than for exercise and in that case at a safe distance from others.”

Everyone should avoid gatherings and crowded places from now on, said Mr Johnson, even if they are in good health and have no virus symptoms.

“Now is the time for everyone to stop non-essential contact with others and to stop all unnecessary travel,” he said.

By the weekend, those groups most vulnerable to Covid-19 will be asked to stay at home for 12 weeks to ensure they are “largely shielded from social contact”, he said.

This includes over-70s, pregnant women and people with medical conditions including heart disease, respiratory illnesses, diabetes, or people undergoing cancer treatment.

“What we are announcing today is a very substantial change in the way that we want people to live their lives and I can’t remember anything like it in my life time,” said Mr Johnson.

First Minister Nicola Sturgeon said the measures being rolled out across the UK would “change life as we know it”.

She said: “We are now on the cusp of a rapid acceleration of the spread of coronavirus. We could see a doubling of cases every few days.

“We must step up the measures that we take to slow the spread, to protect our National Health Service and its ability to provide care and treatment to those that need it and also, crucially, to save lives.

“There is no way of escaping that what we are advising people now to do will significantly and substantially change life as we know it for a considerable period of time.

“We are all in this together. If we do the right things, if we all follow the advice that is being given, we can get through this and we will get through this. She called on Scots to stay away from crowded places such as pubs or cinemas.

However, Professor Jason Leitch, Scotland’s national clinical director, said elderly people would be expected to reduce social contact such as going to the pub, bingo or church without being cut off from loved ones or quarantined indoors.

He said: “In fact, quite the opposite, we expect family contact to increase in that group so that those people will be looked after. The last thing that we want is four months of loneliness.”

Health Secretary Jeane Freeman said extra ventilators had been ordered for intensive care units, which will take the total to 700, and confirmed that the GP surveillance testing system – normally used to monitor seasonal flu outbreaks – would be expanded from 42 to 200 GP practices.

It will now be used to test those with relevant symptoms in a bid to pick up virus hotspots and monitor how the disease is spreading.

Scotland’s chief medical officer, Dr Catherine Calderwood, said she hopes to have a vaccine in place by early 2021.

It came amid reports that a Japanese man had tested positive for coronavirus for a second time, two weeks after he recovered from the potentially deadly infection.

The man, who is in his 70s, was initially infected while on board the disease-ridden Diamond Princess cruise ship in February.

He was treated in a medical facility in Tokyo and returned to his home in Mie after tests for Covid-19 came back negative, according to local media reports.

Not long after being told he was in the clear, the man fell ill with a fever and temperature of 39°C once again.

He was diagnosed with Covid-19 on Saturday. It’s not the first time a patient has been “reinfected” with the virus, after a Japanese woman was diagnosed again two weeks after her recovery.

The possibility of re-infections raises difficult questions about the prospects for a successful vaccine and herd immunity – the process by which enough people within a population have contracted and recovered from an infection to be protected against catching or spreading it in future.

However, a study on monkeys, published yesterday, found that the animals appeared to develop immunity against the virus after being infected with it in the lab.

Meanwhile, a 21-year-old Spanish football coach has died of coronavirus, after doctors also diagnosed him with leukaemia.

Francisco Garcia, who managed the junior team of Malaga-based club Atletico Portada Alta, is believed to be the youngest victim of the virus in the world so far.

He did not realise that he had the blood cancer when symptoms of the virus began to worsen. Leukaemia patients are among those most at risk.

The European Union announced plans to close its borders to all non-essential travel as it attempts to curb the spread of coronavirus.

The temporary restrictions would ban people from travelling in and out or within the bloc “for an initial period of 30 days” and could be prolonged, according to European Commission President Ursula von der Leyen.

Essential staff such as doctors and nurses and people transporting goods to the EU will be exempt from the upcoming measures.

“The less travel, the more we can contain the virus,” Ms von der Leyen said.

It came as Virgin Atlantic said it was cutting four-fifths of its flights and has asked staff to take eight weeks of unpaid leave.

Ryanair and EasyJet are grounding most of their fleets, while BA owner IAG is to cut capacity by 75 per cent.

Holiday company Tui is also suspending the “majority” of its operations, affecting “package travel, cruises and hotel” bookings. Much of the continent is already in lockdown.

Spain declared a state of emergency on Saturday and has ordered people to stay in their homes unless they are going out to buy food or medicine, go to work or hospital.

It has also closed restaurants, bars, most retail shops and reduced public transport.

Spanish health authorities said deaths from the coronavirus had soared in 24 hours to 342, with total infections at nearly 10,000.

In Italy, 349 deaths were recorded in just 24 hours, taking the total number over 2,000 for the first time.

Its death rate from coronavirus – measured by the number of deaths for every 100,000 people – is now the highest in the world.

The latest figures came as leaked documents revealed that Italian coronavirus patients who are 80 or older will not receive intensive care if the crisis worsens.

The emergency plans drawn up by civil protection officials in Turin warn that “it will be necessary to apply criteria for access to intensive treatment” if there are too many patients.

The document proposes that these criteria “must include age of less than 80”.

Meanwhile, Germany has announced plans to close most shops, limit restaurant opening hours and ban religious services, after recording more than 1,100 new cases in a single day.

It has also imposed border controls with Austria, Denmark, France, Luxembourg and Switzerland.

Chancellor Angela Merkel asked for citizens’ co-operation. “The better everyone sticks to these rules, the faster we’ll get through this phase,” she said.

The World Health Organisation also called on all countries to ramp up their testing programmes as the best way to slow the pandemic. “We have a simple message to all countries – test, test, test,” said WHO Director General Tedros Adhanom Ghebreyesus.

“All countries should be able to test all suspected cases, they cannot fight this pandemic blindfolded,” he added. The strategy to contain the disease, by finding people with infections and rapidly isolating them, was still the best approach, said the WHO chief.