The main hospital in Dunedin, a South Island city of more than 122,000 people, was effectively shut down on Monday after 74 patients and staff contracted the highly infectious norovirus in the last three weeks, the dpa reported.
More than 800 people scheduled to have surgery or out-patient appointments with doctors and specialists were told to stay home as the virus continued to spread over the weekend, news reports said.
Security guards were posted at the doors on Saturday to turn away visitors, with only the accident and emergency department remaining open to the public.
Officials said another 17 cases of norovirus, which causes stomach cramps, vomiting and diarrhoea, were reported over the weekend. It was not known when the hospital would be fully operational again.