Two members of the same family have tested positive for coronavirus in England.
The first cases of the virus to be diagnosed in the UK were announced as more than 80 Britons on an evacuation flight from the Chinese city at the centre of the outbreak were due to land in the UK.
The Department of Health declined to say where in England the patients were from but it is understood they are not in the Wirral area, where a special facility has been set up to quarantine those returning from Wuhan.
In a statement, chief medical officer Professor Chris Whitty said: "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 and we have robust infection control measures in place to respond immediately.
"We are continuing to work closely with the World Health Organisation and the international community as the outbreak in China develops to ensure we are ready for all eventualities."