Public Health England (PHE) is urgently trying to trace anyone who came into contact with the two people who have tested positive for the coronavirus in the UK.

England’s chief medical officer, Prof Chris Whitty, said: “We can confirm that two patients in England, who are members of the same family, have tested positive. The patients are receiving specialist NHS care and we are using tried and tested infection control procedures to prevent further spread of the virus.”

It is understood that the pair travelled to the UK from China recently and are believed to be Chinese nationals. They are undergoing treatment at the specialist Airborne High Consequence Infectious Diseases Centre in Newcastle’s Royal Victoria Infirmary.

Cases in the UK have long been expected. The virus has already spread to 22 other countries outside China.

The pair had been at the StayCity apartment hotel in York when they became ill. A StayCity spokesman said: “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. The apartment concerned will undergo a thorough environmental clean and disinfection by a specialist contractor.”

Public Health England (PHE) is urgently trying to trace anyone who came into contact with the two people. It said steps would be taken to reduce the risk to the public and it was “identifying the areas where there is deemed to be a risk”.

Professor Sharon Peacock, director of the National Infection Service at PHE, said: “Public Health England is contacting people who had close contact with the confirmed cases. 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.”

Prof Peacock previously 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.

The PHE definition of close contact is being within two metres of the infected person for 15 minutes.

Guests were continuing to check in for weekend breaks in York on Friday. Outside the hotel, two guests told the Guardian that as recently as Friday morning they had been told by reception staff that reports that two tourists had been taken ill from their apartment on Wednesday were “lies”.

“This morning they said it was a lie and not to listen to it,” said Andy Neale, 21, who was staying at StayCity for the night with his girlfriend. “It’s not ideal. They should’ve taken some precaution.”

He said the incident had marred the couple’s getaway. “My girlfriend is stressing out, she’s using hand wipes on everything.”

A family who were staying in the hotel on a visit from Asia to see their daughter, who is a student in York, said they had been told the reports of cases were “false information”.

The PHE supported the decision not to close the hotel. It said: “The design of the accommodation means that there is minimal interaction between guests and, following a risk assessment by our experts, closing the accommodation was not necessary. Appropriate infection and prevention control measures are being implemented.”

Earlier, Whitty said: “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 and we have robust infection control measures in place to respond immediately. We are continuing to work closely with the World Health Organization and the international community as the outbreak in China develops to ensure we are ready for all eventualities.”

Q&A How can I protect myself and others from the coronavirus outbreak? Show The World Health Organization is recommending that people take simple precautions to reduce exposure to and transmission of the coronavirus, for which there is no specific cure or vaccine. The UN agency advises people to: Frequently wash their hands with an alcohol-based hand rub or warm water and soap

Cover their mouth and nose with a flexed elbow or tissue when sneezing or coughing

Avoid close contact with anyone who has a fever or cough

Seek early medical help if they have a fever, cough and difficulty breathing, and share their travel history with healthcare providers

Advice about face masks varies. Wearing them while out and about may offer some protection against both spreading and catching the virus via coughs and sneezes, but it is not a cast-iron guarantee of protection Many countries are now enforcing or recommending curfews or lockdowns. Check with your local authorities for up-to-date information about the situation in your area. In the UK, NHS advice is that anyone with symptoms should stay at home for at least 7 days. If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home.

The chief medical officers for the four countries of the UK raised the risk level from low to moderate on Thursday evening in the wake of the WHO declaring coronavirus to be an international emergency. The UK has been on high alert for days, with 177 people tested for the virus, of whom 175 proved negative.

In recent days ambulance workers and paramedics have been seen in protective suits in a number of places. As well as the York incident, a man was taken away from student accommodation in London. The University of Bristol said one person admitted to hospital with symptoms as a precaution had been discharged after being cleared of coronavirus.

The UK had comprehensive plans in place for dealing with the arrival of the Wuhan coronavirus. It also has a good track record. Several cases of Mers – Middle East respiratory syndrome, which is also caused by a coronavirus – have been diagnosed in the past in travellers and in two healthcare workers who were infected by patients before anyone realised they had the virus. All were nursed in hospital infectious disease units and recovered.

Paul Hunter, a professor in medicine at the University of East Anglia, said: “The report of the first two cases diagnosed positive for 2019-nCoV in the UK is not surprising and was almost inevitable. The chief medical officer’s statement gives no information on where these two members of the same family acquired their infection. The two cases are members of the same family but no information has been released about whether both cases will have been infected simultaneously or whether one would have passed the infection to the other.

“The NHS is well able to nurse people with this novel coronavirus as it has successfully and safely managed a number of cases of both Sars and Mers in the past. With the information available it is not possible to judge what risk if any there may be of spread within the community.”