St. Paul's Hospital says there were more new cases of diarrhea and vomiting among patients and staff on Tuesday.
Hospital officials say members of the public who are scheduled for day surgeries can still keep their appointments but will be restricted to a specific care area.
The emergency department will remain open, but hospital officials are urging people to come only in a true emergency.
Urgent and emergency surgeries will proceed as scheduled.
Hospital officials say there will be some exceptions to the new measures, such as people visiting a dying relative, but asks those visitors to contact the nursing unit affected in advance.
The outbreak started last week.
Though often associated with food preparation, the region says viruses like Norwalk, which are not airborne, still often spread in hospitals because of close-quarters and shared washrooms.