All non-urgent surgical operations have been cancelled at three hospitals in Cornwall affected by the winter vomiting bug norovirus.
Several wards have been closed at the Royal Cornwall Hospital in Truro and some patients moved to other hospitals.
The bug has also resulted in the closure of a ward at the West Cornwall Hospital in Penzance, and St Michael's Hospital in Hayle is also affected.
The decision to halt routine surgery was taken to ease pressure on services.
A spokesperson for the Royal Cornwall Hospitals NHS Trust said the move would also help reduce the number of people coming to the hospitals.
Norovirus is highly contagious and visitors have been asked to stay away unless they are going to see someone who is critically ill.