Health officials are trying to discover how a man from Surrey caught coronavirus, after he became the first person to be infected within the UK.
The man had not been abroad recently – unlike the 19 others who have tested positive in the UK.
Officials are trying to trace people who had contact with him. He had attended Haslemere Health Centre which was later closed for “deep cleaning”.
The government is preparing to publish emergency plans to tackle the virus.
The package of measures within the emergency legislation would be designed to help the public sector – such as the NHS and schools – cope with a serious rise in cases.
There are few details about what the measures could involve – but school class sizes in England is one area which would be addressed. They would be permitted to rise above statutory limits, in the event of widespread teacher absences.
Health minister Edward Argar told BBC Radio 4’s Today programme that “any responsible government” would have “contingency planning” in place, but added the government was “entirely focused on making containment work”.
The plans, which are expected to be published next week, “are not needed at the moment,” he added.
On Friday, a British man became the first UK citizen to die from coronavirus after being infected on the Diamond Princess cruise ship quarantined in Japan.
Prime Minister Boris Johnson, who said the virus outbreak was now the government’s top priority, will chair a meeting of the government’s Cobra emergency committee on Monday.
He had faced criticism from Labour, who said he needed to “get a grip” on the situation and questioned why he was waiting until next week to hold the meeting.
Nearly 9,000 people in the UK have so far been tested for coronavirus.
On Friday, the number of people who have tested positive in the UK reached 20, after the man in Surrey was diagnosed.
He has been transferred to a specialist NHS infection centre at Guy’s and St Thomas’ Hospital in central London.
Who did this man catch the virus from?
This is the urgent question that needs answering about the 20th case in the UK.
So far, no connection with anyone who has travelled to an affected country has been discovered.
Until we know the answer it is difficult to know how big a development this is.
This could be an “outbreak of two” – with just one other, still to be identified, person that caught coronavirus abroad.
Or is this the first case to be detected from a much larger outbreak? We know this can happen, Italian scientists believe the virus was circulating there unnoticed for weeks.
For now, we simply do not know, but this is a scenario officials have been preparing for.
Health minister Helen Whately told BBC Newsnight work said it was “likely” that more cases will be seen within the UK.
She said members of the public were not recommended to wear face masks, but that “everybody has a part to play to help us be prepared as a country”.
What do I need to know about the coronavirus?
- WHAT ARE THE SYMPTOMS? A simple guide
- WAYS TO PREVENT CATCHING IT: How to wash your hands
- WHERE ARE WE WITH A VACCINE? Progress so far
- A VISUAL GUIDE TO THE OUTBREAK: Virus maps and charts
- WHAT DOES IT MEAN FOR MY HOLIDAY? Your rights as a traveller
People should wash their hands thoroughly, and carry a tissue to sneeze or cough into to reduce the spread of the virus, according to public health advice.
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Of the most recent case, the Department of Health said the virus was passed on in the UK but the original source was “unclear” and there was no “immediately identifiable link” to overseas travel.
Dr Nathalie MacDermott, from King’s College London, told the Today programme the Surrey case was “alarming” because it becomes more difficult to contain the virus when it is not clear who patients have been infected by.
But she added the government’s “worst case scenario” planning should not be a source of concern.
“It’s important that we all prepare for the worst but that we don’t necessarily panic and assume the worst,” she said.
Meanwhile, six British guests have left a quarantined hotel in Tenerife after four days of isolation.
Local officials said 48 more Britons may leave the Costa Adeje Palace on Saturday.
The 54 guests were considered “low risk” because they arrived after people infected with the virus had left the hotel.
The BBC’s Fiona Trott said some of the other Britons at the hotel have received a letter from the Foreign Office telling them they will be tested for Covid-19.
Airline Jet2 has said it would only fly passengers back to the UK if they had completed a 14-day quarantine at the hotel, or tested negative for the virus.
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In addition to the Surrey patient, three other cases of the virus were confirmed in the UK on Friday, including the first one in Wales.
Two new patients in England contracted the virus while in Iran, the Department of Health said.
Public Health Wales said it was working to identify close contacts of the Welsh patient, who is believed to be from the Swansea area and was infected in northern Italy before returning to the UK.
Northern Ireland confirmed its first case on Thursday. Everyone who had been in close contact with the woman has been notified, officials have said.
The World Health Organization has raised its global risk assessment of the virus to its top level, “very high”.
Globally, more than 80,000 people have been infected. About 2,800 have died – the vast majority in China’s Hubei province.
Fear about the virus has continued to hit global stock markets.