CORONAVIRUS is spreading across the UK faster than experts first feared, the PM warned today.
Speaking at the first of daily briefings, Boris Johnson warned without "drastic action" cases will double every five to six days.
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It comes as the number of recorded cases surged by 171 to 1,543 and the UK death toll leapt from 37 to 53.
Boris Johnson urged Brits to avoid unnecessary social interactions and non-essential travel, telling people to stay away from pubs, clubs and mass gatherings.
He said without action, cases in the UK could "double every five to six days".
Mr Johnson added that from Tuesday mass gatherings are something "we are now moving emphatically away from".
'Dampen the curve'
Chief scientific adviser Patrick Vallance warned we are "on the cusp of a major growth" in cases, with London ahead of the rest of the UK.
He said the measures introduced by the PM are designed to try and "dampen the curve" to delay the peak in cases and keep people safe.
"Most people have a mild disease, but some do not," he warned.
"This is a very fast moving situation. We're on the cusp of a very fast moving period."
Sir Patrick said the latest moves to combat the spread, which include advising against unnecessary social interaction and non-essential travel, would have a "big effect".
"This is not a series of small interventions," he added.
"You would anticipate that this could have a dramatic effect to reduce the peak and to reduce death rates.
"They are not easy but they are important and they will have the effect if we all do it.
"This is a matter for us to take accountability to make sure we help each other, protect ourselves and protect the NHS."
'Fast upswing'
Sir Patrick also said the UK is now looking "more like three weeks" behind Italy, the epicentre of the European outbreak of Covid-19.
He said: "At the early stages in an outbreak, the numbers are quite small so actually the precision with which you can predict exactly where you are is low.
"I said perhaps we were four-weeks behind where Italy was, I think the new numbers suggest we're maybe more like three-weeks in terms of that."
He added: "Importantly, it looks like we're on the fast upswing or just about to get there and that's the reason to want to get in quite quickly with these measures."
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Chief medical officer Chris Whitty said: "This disease is accelerating up the curve, it is still at a low level but it will now accelerate quite rapidly now.
"The next few months are going to be extraordinarily difficult for the NHS and colleagues."
He added: "Chances of dying very low.
"Some people will not get the infection, some people will have no symptoms at all.
"Of those who do have symptoms the majority will have a mild disease, they can easily manage at home meaning they don't have to go to the NHS.
"A small minority get significant disease, a small proportion will need intensive care and sadly a small number will go on to die.
"We know older people are at greater risk.
"But being old doesn't mean you will get it worse."
What are the signs of Covid-19?
As Covid-19 is a new virus, experts are still working to understand it.
However, health officials say the most common symptoms of coronavirus infection usually include:
- A dry cough
- A high temperature
- Shortness of breath
Some patients may have aches and pains, nasal congestion, runny nose, sore throat or diarrhoea - but these are usually mild and begin gradually.
Developing these symptoms does not necessarily mean you have the illness and they are similar to other illnesses, such as the common cold or flu.
Some people will not develop all of these symptoms - and some might not even show symptoms at all, experts say.
Mr Johnson also introduced new tighter measures for Brits as he set out the need for "drastic action" to tackle the "fast growth" of coronavirus.
As part of the measures, anyone living in a household with somebody who has either a persistent cough or fever must now also isolate themselves for 14 days.
All people should avoid gatherings and crowded places, while people who are vulnerable - including those are elderly - will need to undertake even more drastic measures.
Earlier today, Dr Tedros of the World Health Organization warned: "In the past week, we have seen a rapid escalation of cases of Covid-19.
"More cases and deaths have now been reported in the rest of the world than China."
MORE ON CORONAVIRUS
Britain's chief medical adviser Chris Whitty said Britain will continue to scale up testing after the World Health Organisation said doing so was critical in the fight against the epidemic.
"We will continue to scale up the testing every single week from here on in," he said.
"It is important to realise the scale of UK testing, which has been substantial."