Prime Minister Jacinda Ardern told RNZ's Morning Report one of the new cases is a nurse at Auckland Hospital.
"The health workforce are very well versed and mapping these issues and have done in the past.
We have had COVID-positive cases in our health workforce before. What's different on this occasion is that we have this individual who is fully vaccinated."
Ardern said the four new cases were the workmate of the 58-year-old Devonport man and the workmate's close or household contacts.