A coronavirus outbreak has been declared at Newport's Royal Gwent Hospital.
Aneurin Bevan University Health Board said 14 patients across three adult wards had been affected.
No staff have tested positive and no affected patients have been admitted to intensive care, it said.
A no visiting policy has been reintroduced at the hospital, with the exception of visits agreed for maternity and paediatric patients.
Cwm Taf Morgannwg University Health Board is also dealing with outbreaks at three of its hospitals - Royal Glamorgan Hospital in Llantrisant, Prince Charles Hospital in Merthyr Tydfil and Bridgend's Princess of Wales Hospital
The hospital outbreak was declared at the Royal Gwent on the advice of the Infection Prevention and Control Team and the Lead Infection Control Doctor, the health board said.