Public Health England has confirmed that two people who were diagnosed with coronavirus had been staying in a hotel at York when they became unwell.
They are now urgently trying to trace people who came into contact with them during their stay.
On Wednesday night, the Staycity Hotel on Paragon Street, near York Barbican, was put on lockdown when a man, understood to be a Chinese national, was taken to hospital after falling ill. Witnesses saw paramedics wearing quarantine suits treat him at around 8pm.
The pair are being treated by Newcastle upon Tyne Hospitals NHS Foundation Trust in its specialist Airborne High Consequences Infectious Disease Centre (HCID).
It is understood that they travelled to the UK from China recently and are undergoing treatment at the Newcastle Royal Victoria Infirmary.
City of York Council leader, Coun Keith Aspden insisted that all was being done to make sure that the city was safe for residents and visitors in the wake of the announcement.
"First and foremost, I would like to update residents and visitors that the council has received guidance from specialist services and we are working with our partners to ensure that York remains a safe place for everyone to live, work and visit," he said.
"The council has been in close contact with Public Health England, the Department for Health and Social Care and local NHS partners.
"We are confident that all the relevant services in the city are well-equipped and ready to respond if appropriate."
Prof Sharon Peacock, Director of the National Infection Service, Public Health England, said on Friday: “Public Health England is contacting people who had close contact with the confirmed cases.
"The two cases were staying in York when they became unwell.
"Close contacts will be given health advice about symptoms and emergency contact details to use if they become unwell in the 14 days after contact with the confirmed cases.
“This tried and tested method will ensure we are able to minimise any risk to them and the wider public.”
Earlier, Prof Peacock said that while staff are working to trace people who have been in contact with the pair, they do not currently have "any idea" of how high that number might be.
Staycity Aparthotels York has also confirmed two guests staying in their hotel have tested positive for coronavirus.
A spokesperson said: "We have now received confirmation that two guests staying in one of our apartments in York have been tested positive for the coronavirus.
"We have been advised by Public Health England that there is minimal ongoing risk of infection to either guests or staff, and as such our York property remains open for business.
"In due course the apartment concerned will undergo a thorough environmental clean and disinfection by a specialist contractor.
"We would like to reassure all our guests that we are following official advice on this matter and that the health and safety of everyone working and staying in our properties remains of paramount importance to us."
The Public Health Matters website states: "Two patients in England, who are members of the same family, have tested positive for novel coronavirus (2019-nCoV). The patients are receiving specialist NHS care, and we are using tried and tested infection control procedures to prevent further spread of the virus.
"The NHS is extremely well-prepared and used to managing infections and we are already working rapidly to identify any contacts the patients had, to prevent further spread.
"We have been preparing for UK cases of novel coronavirus (2019-nCoV) and we have robust infection control measures in place to respond immediately.
"This is a rapidly evolving situation which we are monitoring carefully but based on the available evidence.
"NHS and PHE have an established plan to respond quickly and reduce the risk to others if people contact us to say they have symptoms and have recently travelled to China."
The following advice has also been issued on the Public Health Matters website.
What is coronavirus and what are the symptoms?
A coronavirus is a type of virus. As a group, coronaviruses are common across the world.
Typical symptoms of coronavirus include fever and a cough that may progress to a severe pneumonia causing shortness of breath and breathing difficulties.
Generally, coronavirus can cause more severe symptoms in people with weakened immune systems, older people, and those with long term conditions like diabetes, cancer and chronic lung disease.
What is the current risk level in the UK?
Based on the World Health Organization’s declaration that this is a public health emergency of international concern, the UK Chief Medical Officers have raised the risk to the public from low to moderate.
This permits the government to plan for all eventualities. The risk to individuals in the UK has not changed at this stage. Our advice for travellers from Wuhan remains unchanged.
As of 31 January, a total of 177 tests have been concluded, of which 175 were confirmed negative and 2 positive.
The latest information and advice is available at https://publichealthmatters.blog.gov.uk/2020/01/23/wuhan-novel-coronavirus-what-you-need-to-know/.”