Prime Minister Boris Johnson has upgraded the government advice on coronavirus, telling Britons to avoid public gatherings, work from home if they can, and self-isolate for 14 days if they or someone in their family household has a symptom of coronavirus.

Mr Johnson told Britons at a press conference given from Downing Street on Monday that according to modelling by his chief medical and scientific officers, “it looks as though we are approaching the fast-growth part of the upward curve” of the COVID-19 pandemic “and without drastic action, cases could double every five or six days”.

As a result, the government guidance is that if you have one of two symptoms — a new persistent cough or a high temperature — that you should self-isolate for 14 days. All others in your household should also isolate 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,” the prime minister said. If that is not possible, Mr Johnson advised that people should “do what you can to limit contact when getting them yourself”.

The point about self-quarantine was reiterated by the government’s chief medical officer Professor Chris Whitty, who spoke after the prime minister to say: “If one person in the household has symptoms, the whole household stays at home.”

“Now is the time for everyone to stop non-essential contact with others and to stop unnecessary travel,” the prime minister also said. “We need people to start working from home where they possibly can and you should avoid pubs, clubs, theatres, and other such social venues.”

“From tomorrow, we will no longer be supporting mass gatherings with emergency workers in the way that we normally do,” he added, and further advised Britons against attending large scale public events.

Those with the most serious medical conditions were told to isolate themselves for 12 weeks. External borders remain open, as do the country’s schools.

The government’s chief scientific adviser, Sir Patrick Vallance, said that the UK was currently three weeks behind Italy in terms of the spread of the China-origin virus.

Today’s was the first of Downing Street’s daily televised coronavirus press conferences, which will be chaired by either the prime minister or a member of his team. The policy was put into place after criticisms of Number 10’s apparent lack of transparency with the public over the government’s efforts to protect Britons and halt the spread of the contagious, deadly infection.

The health secretary confirmed after the press conference that there have been 53 deaths from COVID-19 in the UK.