The government’s chief scientific adviser has said that 60 per cent of Britons need to catch coronavirus to develop “herd immunity” because the virus could return like the winter flu.

“We think this virus is likely to be one that comes year on year, becomes like a seasonal virus,” Sir Patrick Valance said.

“Communities will become immune to it and that’s going to be an important part of controlling this longer term. About 60 per cent is the sort of figure you need to get herd immunity,” he told Sky News on Friday.

As of Thursday, there are 590 confirmed cases of COVID-19, with ten fatalities, but Sir Patrick said that the true number of people infected could be between 5,000 and 10,000. There is currently no vaccine.

The World Health Organization categorised the outbreak as a pandemic on Wednesday, a designation given to a disease for which people have no natural immunity that spreads around the world beyond expectation.

On Thursday, Prime Minister Boris Johnson announced that the UK was going into the second phase of dealing with the outbreak, from trying to contain the virus to delaying the spread.

Addressing the public during a press conference on Thursday, Mr Johnson said: “We have all got to be clear, this is the worst public health crisis for a generation. Some people compare it to seasonal flu. Alas, that is not right. Due to the lack of immunity this disease is more dangerous.

“It is going to spread further and I must level with you, I must level with the British public: many more families are going to lose loved ones before their time.”

Face-to-Face Brexit Talks with EU Cancelled over Coronavirus https://t.co/PgWOH74QZS — Breitbart London (@BreitbartLondon) March 13, 2020

Mr Johnson added that the most dangerous period of the infection was some weeks away, saying: “At some point in the next few weeks we are likely to go further, and if someone in a household has those symptoms then we will be asking everyone in that household to stay at home. I want to signal now that this is coming down the track.”

Much of the prime minister’s recommendations and action remains unaltered, with the only notably new advice being: if a person is experiencing coronavirus-like symptoms — a dry cough and fever — they are advised to self-isolate at home for at leave seven days. The government also recommends against foreign school trips and urges older citizens to refrain from going on cruises.

By contrast, countries like Italy and Ireland have closed schools and restricted public gathering. The Czech Republic followed U.S. President Donald Trump’s lead and enacted a travel ban, stopping entry of foreigners from 13 countries.

The prime minister has also decided to not close the House of Commons despite a junior minister being diagnosed with coronavirus. The outbreak is starting to affect aspects of British political life, however, with the government announcing on Thursday that planned UK-EU negotiations set to take place in London next week have been cancelled. Both parties are exploring options to continue talks over the telephone or video conferencing.

Minster Michael Gove has said that delays to negotiations due to coronavirus will not impact the UK’s scheduled departure from the Single Market and Customs Union on December 31st, 2020.