Dunedin Hospital is in lockdown mode after 50 patients and staff were diagnosed with the gastro infection norovirus over the past three weeks.
Hospital operations manager Megan Boivin says only staff bearing identification badges are being allowed in.
Ms Boivin says two wards have had to be closed and security guards are manning the hospital's entrances.
"We had further staff members and patients showing the signs and symptons of the virus, namely, diarrhoea and vomiting," she says.
"At that stage we decided to put the hospital on what we call full lockdown which means that we are asking visitors to stay away. "
She says managers will meet on Sunday morning to decide whether to continue the lockdown.