Two wards at Noble's hospital are closed to new admission following an outbreak of a vomiting break.
Health authorities have shut wards 5 and 8 to new patients as a precaution due to a suspected bout of viral gastroenteritis.
Visitors aren't banned, but the public is being urged not to visit the hospital unless absolutely necessary and not to take children under 12 year old to visit patients.
Anyone who has had symptoms of a stomach bug in the last three days is asked not to visit the hospital.
The Department of Health and Social Care admits the closures place remaining wards under strain, with few beds available for emergency and elective admissions.
Those with operations scheduled for the coming days are warned that cancellations are possible.
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