Hospitals in Dunedin and Lower Hutt say no more staff or patients have fallen ill with what is suspected to be norovirus.
Seven patients at Hutt Hospital and five patients and a staff member at Dunedin Hospital have fallen ill, although it is not yet known if norovirus is responsible.
Both hospitals have isolated the wards involved, and Hutt Hospital says it has now discharged one patient.
The wards will remain closed until Wednesday morning, when the situation will be reassessed.
Hutt Hospital says it expects to receive test results on Wednesday which will show whether the outbreak has been caused by norovirus.
Dunedin Hospital is dealing with a "code black" bed shortage, its highest alert.
In August, an outbreak of norovirus affected 160 people at the hospital.