The UK has seen its biggest day-on-day increase in coronavirus cases, with 87 people now confirmed to have the virus.
Three of the 32 new cases recorded in England were passed on in the UK, raising fears that community transmission may now be taking hold.
The jump comes as England’s chief medical officer, Professor Chris Whitty, warned that a UK epidemic is looking “likely”.
Boris Johnson told MPs that people who self-isolate are “helping to protect all of us by slowing the spread of the virus”.
He added: “If they stay at home and if we ask people to self-isolate, they may lose out financially.
“So, I can today announce that the Health Secretary will bring forward, as part of our emergency coronavirus legislation, measures to allow the payment of statutory sick pay from the very first day you are sick instead of four days under the current rules, and I think that’s the right way forward.
“Nobody should be penalised for doing the right thing.”
Prof Whitty said the new cases in the UK included 32 patients from England.
“Three additional patients contracted the virus in the UK and it is not yet clear whether they contracted it directly or indirectly from an individual who had recently returned from abroad. This is being investigated and contact tracing has begun.”
The Department of Health has been updating the UK figures daily, with one Northern Ireland case among the 85 recorded at 2pm on Wednesday.
However, Northern Ireland later confirmed two more cases, taking the UK total to 87.
Earlier, Prof Whitty told the BBC there could be a need to do “extreme things” to protect the elderly and those with pre-existing health conditions.
He added: “At this point in time we think it is likely, not definite, that we will move into onward transmission and an epidemic here in the UK.”
But he stressed that for most people, “this will be a mild or moderate disease, anything from a sniffle to having to go to bed for a few days, rather like with mild flu”.
On the NHS, Prof Whitty said: “The NHS will always cope because the NHS is an emergency service which is very good at adapting to what it finds itself with.”
But he said if the UK sees a very large epidemic, “then it will put very high pressure on the NHS”, and there could be “several weeks which could be very difficult” for the health service and wider society.
Prof Whitty suggested that shutting down cities in the UK would not be effective now.
He said: “Closing cities is really only appropriate if you have a significant epidemic in one particular place and almost nothing anywhere else.
“It made sense for China to respond in the way it did but it would be very unlikely here … This is now in multiple places in Europe and around the world.”
He added: “However, the latest case numbers do not suggest we are past the stage where the containment approach is no longer valuable. Even though the increase looks dramatic, it should not alter our strategy at the moment.”
As cases in the UK climb, the Department of Health said it would no “longer be tweeting information on the location of each new case”.
It said: “Instead, this information will be released centrally in a consolidated format online, once a week. We are working on this now and plan to share on Friday.”
Of new cases announced by regional bodies on Wednesday, two people are from Carlisle and both had recently returned from a trip to northern Italy.
One is a member of healthcare staff at the Cumberland Infirmary.
Another patient who was admitted to Wythenshawe Hospital in Manchester has also tested positive for Covid-19.
Lancashire County Council said two cases of coronavirus had been confirmed in South Ribble.
The two people had recently travelled to Italy and were isolating themselves at home, a council spokesman said.
Meanwhile, students at Goldsmiths in south London have been informed that a visitor to one of the university’s halls of residences had tested positive for the virus.
Three cases of coronavirus have been confirmed in Trafford, one in Oldham, Greater Manchester, and a spokesman for Liverpool City Council confirmed one case in Liverpool.
Buckingham University and the University of London said they had delayed their graduation ceremonies to minimise the spread of the disease.
And Britons who have returned from the Costa Adeje Hotel in Tenerife since Monday have been advised to self-isolate after a case of coronavirus was diagnosed at the hotel on March 2.
Elsewhere, the London Book Fair at Olympia from March 10 to 12 was cancelled after major publishers pulled out amid coronavirus fears.
It sets out that a level 4 NHS incident has been declared – the highest level – meaning extra steps are needed.
Former business secretary Andrea Leadsom said preparations for a no-deal Brexit had aided the Government’s response to the coronavirus outbreak.
She told Sky News: “Ironically, I think a lot of the work we did last year preparing for the supposed no-deal Brexit on 31 October has stood the Government in incredibly good stead – looking at packages of support and how you might be able to help companies keep going should something dramatic happen.
“I’m quite sure that some of that will be being dusted off with a view to looking at how that could be adapted.”
A new Government publicity campaign seeks to drive home the message that regular hand-washing is the single most important action individuals can take in the fight against Covid-19.
The new adverts say hand-washing should be for 20 seconds, using soap and water or hand sanitiser.
Government scientific experts predict the UK’s coronavirus outbreak could last around four to six months.
Globally, there are now more than 90,000 cases worldwide, with more than 3,000 deaths.
Scotland’s First Minister Nicola Sturgeon told ITV: “The containment phase is really important.
“In Scotland, we have confirmed at this point three cases, I would expect that to rise, perhaps, significantly in the days to come.
“But we are still very focused on stopping the spread from individual to individual.
“We shouldn’t lose sight of that right now.
“And the public can help with that by following all the, I know, very basic sounding, but very important advice on hand-washing and other personal hygiene.”