Northern Ireland has diagnosed its first case of coronavirus, bringing the UK's total to 16.
Authorities said the patient had travelled from northern Italy via Dublin and had showed a presumptive positive result, which would be confirmed by a lab in England.
It comes after health officials confirmed two new cases of the virus in England earlier on Thursday.
Those patients contracted the virus while they were in Italy and Tenerife.
Northern Ireland's chief medical officer Dr Michael McBride said: "We have been planning for the first positive case in Northern Ireland and have made clear that it was a question of when not if.
"We have robust infection control measures in place which enable us to respond immediately. Our health service is used to managing infections and would assure the public that we are prepared."
Dr McBride said the case was not linked to a school trip to Italy. Northern Ireland's Public Health Agency said it is "working rapidly" to trace and check the patient's contacts to prevent further spread.
Also on Thursday, the World Health Organization warned the outbreak had reached a "decisive point" and had "pandemic potential".
For a second day, more cases have been reported outside than inside China.
The person who contracted the virus in Tenerife is from Derbyshire. A school in the county has closed because of the case.
It is not clear which part of the UK the other person is from, but they contracted the virus in northern Italy.
Italy now has more than 500 cases of coronavirus with authorities there reporting that 17 people have died.
'Only a matter of time'
The latest positive test comes after England's chief medical officer, Prof Chris Whitty, warned onward transmission of the virus between people in the UK was "just a matter of time".
He said if the outbreak intensifies, it may be necessary to close schools or stop mass gatherings of people for "quite a long period of time, probably more than two months".
Meanwhile, the Cabinet Office has been in communication with local authorities about their "mass death preparedness", BBC Newsnight understands.
Councils are being asked about their plans to deal with pressures on public services if deaths from coronavirus are severe, including where they might locate new - perhaps mass - burial sites.
As of 27 February, a total of 7,690 people in the UK have been tested for the virus.
Of the 16 who have tested positive, eight have so far been discharged from hospital.
Elsewhere, it is understood about 50 Britons quarantined at a coronavirus-hit Tenerife hotel have been told they can leave.
Some 168 Britons are among 700 guests told to isolate themselves at the H10 Costa Adeje Palace hotel after at least four guests, including an Italian doctor, tested positive for coronavirus.
The Canary Islands minister of health earlier announced 130 guests in total would be able to leave, as they arrived on Monday and did not come into contact with the four Italians who tested positive.
However, it is not yet clear when that will happen or where they will go.
Downing Street said the Foreign Office has been in contact with the UK citizens.
"They are providing them with support, they are also in regular contact with local authorities and tour companies to share information," the prime minister's official spokesman said.
Prof Yvonne Doyle, medical director at Public Health England, said a health protection specialist had been sent from the UK to Tenerife to work with the Spanish authorities to better understand the public health measures in place at the hotel.
What should I do to minimise the risk?
The new cases in England come as the government is set to launch a public information campaign, which will focus on hygiene and how to prevent the spread of infection.
The current advice is to cover your mouth and nose with a tissue or sleeve when you cough or sneeze, throw away tissues immediately after use and wash your hands frequently.
It is also advised to avoid touching your eyes, nose or mouth with unclean hands and avoid close contact with people who are unwell.
What is the travel advice?
The Foreign and Commonwealth Office (FCO) is warning against all but essential travel to 11 quarantined towns in Italy, two cities in South Korea and mainland China.
The Department of Health says anyone who has returned from those specified parts of Italy and South Korea, as well as Iran, since 19 February should call the NHS 111 helpline, stay indoors and avoid contact with others.
Anyone who has returned in the past 14 days from Hubei Province in China - where the FCO has warned against all travel - should do the same.
People should also call the helpline and self-isolate if they are experiencing symptoms - however mild - after returning to the UK from the following places:
- Vietnam, Cambodia, Laos, Myanmar and parts of northern Italy since 19 February
- Mainland China, Thailand, Japan, South Korea, Hong Kong, Taiwan, Singapore, Malaysia or Macau, in the past 14 days
Have you been affected by the coronavirus? Or do you have any information to share? Get in touch by emailing email@example.com.
Please include a contact number if you are willing to speak to a BBC journalist. You can also contact us in the following ways: