Two suspected cases of the respiratory virus MERS have shut the A&E department at Manchester Royal Infirmary.
The patients have been isolated for continued treatment.
"We would like to reassure our patients and the general public that there is no significant risk to public health," said a statement from the local NHS trust.
"Manchester Royal Infirmary accident and emergency department will be closed until further notice while further investigations take place."
MERS (Middle Eastern Respiratory Virus Syndrome) symptoms typically include fever, cough and a shortness of breath.
The World Health Organisation says MERS is contagious but " apparently only to a limited extent" and does not pass easily between people.