Some 12 new patients with confirmed Covid-19 were identified in England over the weekend, bringing the total number of UK cases to 35.
Of the 12 new confirmed cases, six patients had travelled to Italy and two had visited Iran, Chief Medical Professor Chris Witty said on Sunday.
Whether the number of patients from West Yorkshire is singular or plural has not been confirmed, neither has the exact location from which they come from.
Investigations are currently ongoing as to whether they had contracted the virus "directly or indirectly" from an individual who had recently travelled abroad.
Other patients confirmed with the virus after travelling to Italy and Iran are from the Greater Manchester, Hertfordshire, Gloucestershire and London areas.
Three further patients were close contacts of a known Covid-19 case that was transmitted within the UK - believed to be a Surrey resident.
Another new patient, from Essex, has no relevant travel to an affected area, Prof Whitty said.