Millions of Britons will need to contract coronavirus in order to control the impact of the disease which is likely to return "year on year", the government's chief scientific adviser has told Sky News.
Around 60% of the UK population will need to become infected with coronavirus in order for society to have "herd immunity" from future outbreaks, Sir Patrick Vallance said.
Herd immunity is the resistance to a contagious disease within a population because enough people have become immune, and so it is harder for it to spread.
There is currently no vaccine available for coronavirus.
So far, 11 people in the UK who have had COVID-19 - the disease which develops from coronavirus - have died.
The number of confirmed cases in the UK reached 590 on Thursday - up by 134 in 24 hours, although Sir Patrick believes the actual number of people infected in the UK at the moment could be between 5,000 and 10,000.
Sir Patrick described COVID-19 as a "nasty disease" but stressed most people would only experience a "mild" illness.
He described how a majority of the UK's population of more than 65 million would need to be infected with coronavirus for the risk of widespread future outbreaks to recede.
"We think this virus is likely to be one that comes year on year, becomes like a seasonal virus," he told Sky News.
"Communities will become immune to it and that's going to be an important part of controlling this longer term.
"About 60% is the sort of figure you need to get herd immunity."
Despite suggestions the death rate from coronavirus could be around 1% of those infected, Sir Patrick said estimating how many might die was "difficult" because there may be many more people that haven't been detected yet.
"That's why some of the new tests that are being developed now are going to be so important, so we can really understand how this disease is spreading and we don't have a handle on that yet," he added.
The World Health Organisation has declared a global pandemic following the spread of coronavirus across many countries.
Prime Minister Boris Johnson on Thursday confirmed the government is entering the second phase of its response to COVID-19 - moving from trying to contain the virus to delaying its spread.
Anyone with a new persistent cough or a high temperature will now have to self-isolate and stay at home for seven days, while schools have been urged to cancel planned trips abroad.
Sir Patrick is helping to oversee the government's response to coronavirus and defended the UK's strategy in dealing with the disease.
Ministers are facing growing questions about why the UK isn't acting in a similar way to other European countries, such as France and Italy, who have taken measures ranging from banning large gatherings to quarantining the entire population.
Sir Patrick said the UK is "a little bit behind" where the coronavirus outbreak is in other countries due to early action in tracing and isolating those who are infected.
"What we don't want to do is to get into kneejerk reactions where you have to start doing measures at the wrong pace because something's happened," he added.
"So we're trying to keep ahead of it, we're trying to lay out the path so people can see what the actions are that are being advised."
Sir Patrick also described Thursday's action taken by Mr Johnson as "a very big measure", adding: "It's going to have quite a big impact across a number of people, a number of households, a number of people.
"I don't think that's a trivial measure at all."
Banning mass gatherings and isolating entire households are the next steps being considered by the government, Sir Patrick revealed.
But, he argued, most of the transmission of coronavirus occurs in small gatherings rather than larger gatherings.