Widespread transmission of coronavirus in the UK is now “highly likely”, Public Health England (PHE) has said.
Director for Health Protection Paul Cosford said the country must be prepared.
The prime minister will chair a meeting of the government’s emergency Cobra committee later, after the number of UK coronavirus cases jumped to 36.
Senior ministers and health advisers will be told that the virus will present a “significant challenge”.
The official government plan on how to tackle the spread of the virus will be finalised and signed off at the talks.
Boris Johnson will say the NHS is well-prepared and the government will “stop at nothing” to fight the virus.
Professor Cosford said the extent of infection in other countries suggested the UK needed to prepare for more widespread infection.
“We should expect that might be quite challenging for us, it is therefore very important that we do everything we can to reduce the spread of infection,” he said.
It comes after 13 new patients were diagnosed on Sunday.
The latest cases included 12 more in England and the first patient in Scotland, meaning the virus has now reached all four parts of the UK.
A health worker at an NHS cancer centre in Middlesex is also among the new cases.
Three of the new cases in England were linked to a man from Surrey, who was the first patient to not have been abroad recently and was instead infected within the UK.
Meanwhile, more British holidaymakers stuck in a quarantined hotel in Tenerife are preparing to return home once they test negative for the virus.
Around 25 Britons have already left the hotel, but 150 others are now in their seventh day at the H10 Costa Adeje Palace after a group of Italians contracted the virus – and are awaiting test results before they can arrange flights.
Once home, they must isolate themselves until the original quarantine period ends on 9 March.
Last week concerns about the outbreak wiped more than $5tn from global stocks. But prices in Asia began to rise on Monday after Japan’s central bank promised to take action to support the markets.
The government has said its plan if the outbreak worsens could include asking newly-retired doctors and nurses to return to the NHS.
People could also be urged to work from home – and closing schools and cancelling major public events have also not been ruled out.
“There now seems little doubt that it will present a significant challenge for our country,” Mr Johnson is expected to tell the meeting, which will involve the UK’s chief medical adviser as well as Scottish First Minister Nicola Sturgeon.
“This battle plan lays out in detail the measures we could use – if and when they are needed.”
The government has also set up a “war room” in the Cabinet Office to roll out a public health campaign encouraging people to wash their hands for 20 seconds or more.
Where are the latest cases?
On Saturday, three new cases were confirmed in Gloucestershire, Hertfordshire and Berkshire.
One of those was a member of staff at St Mary’s School in Tetbury, Gloucestershire, the primary school confirmed. Another school – Willow Bank Infant School in Woodley, Berkshire – said one of its staff had been infected.
Then, on Sunday, 13 new cases were revealed:
- Three of them were close contacts of the man from Surrey, who was announced as testing positive on Friday. They included another person from Surrey and two people from West Sussex who were all “part of an adult family cluster”, Public Health England said.
- Another new case from Essex had “no relevant travel” and it was unclear how they had contracted the virus.
- The remaining eight had visited affected areas – six to Italy, and two to Iran. They were from London, West Yorkshire, Greater Manchester, Hertfordshire and Gloucestershire.
- Scotland recorded its first case – a patient from the Tayside area who had recently travelled from Italy.
The UK is still in the “containment” phase of the outbreak – one of four phases of the government’s plan:
- Containment – caring for any infected people and identifying their close contacts
- Delay – deciding what actions to take to slow down the spread
- Mitigation – damage limitation if the virus spreads widely
- Research – constant and ongoing work to inform the three other phases
BBC health editor Hugh Pym said the current strategy seems to be to warn that difficult measures may be needed while focusing on trying to contain the spread of the virus.
Labour’s shadow health secretary Jonathan Ashworth said his party “broadly supported” the government’s aims.
But he told the BBC he was concerned about the NHS’s capacity to deal with the virus and urged the government to consider emergency funding.
Labour also wants the health secretary to update MPs on the government’s response so it can be scrutinised.
Meanwhile, Lib Dem MP Layla Moran has written to the health secretary to urge him to make sure people are paid if they have to self-isolate.
The GMB union has also called on NHS trusts to ensure that outsourced staff are given sick pay in suspected cases of Covid-19.
It warned most private companies providing the NHS with cleaners, porters and caterers do not offer sick pay for the first three days.
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
As of 09:00 GMT on Sunday, the Department of Health said a total of 11,750 people had been tested in the UK.
Globally, around 86,000 people have been infected, with cases in more than 50 countries. More than 3,000 people have died – the vast majority in China’s Hubei province, where the outbreak originated in December.
Please include a contact number if you are willing to speak to a BBC journalist. You can also contact us in the following ways: