The outbreak of winter vomiting bug Norovirus has spread from South Tyneside District Hospital to a nearby dementia centre.
Haven Court, in the grounds of the South Shields hospital, is not accepting any new admissions until all current residents are symptom free.
The number of affected cases on the premises, an integrated health and care facility which provides both health and social care for older residents, has still to be revealed.
South Tyneside District Hospital is repeating its appeal to visitors to stay away from both the hospital and Haven Court if they have been feeling unwell with symptoms of diarrhoea and vomiting.
A spokesman said: "The trust is continuing to manage an outbreak within the hospital and working hard to make sure it does not spread any further."
Norovirus, which is very infectious, is the most common stomach bug in the UK.
It is generally mild and most people make a full recovery within one to two days.
People should wait until they have been symptom-free for 48 hours before visiting relatives and friends.
Visiting at both the hospital and Haven Court is also restricted to two visitors per patient and no children under the age of 14
South Tyneside NHS Foundation Trust’s medical director, Dr Shaz Wahid, said: “We continue to have wards closed while we deal with an outbreak of Norovirus.
"Whilst it is a short-lived illness from which most people recover without treatment, we must do all we can to protect vulnerable patients.
"We know how important visiting is to patients, and their relatives, friends and carers, and we really appreciate the public’s support in helping us to protect patients.
"Our infection prevention and control team are working extremely hard to prevent transmission of the illness, including constantly monitoring all ward areas to ensure that appropriate measures are in place so that affected areas can be re-opened as quickly as possible.”