Plans are in place to move crew members to MIQ if it becomes a requirement.
According to the government's managed isolation and quarantine website, the closest facilities are in Christchurch.
Health officials were in ongoing communication with the Mattina's captain and were speaking to all crew at least daily to discuss their symptoms and wellbeing, McLeod said.
The crew were tested earlier this week after they notified health officials ahead of their arrival that two of its members were displaying flu-like symptoms.
Both provided negative pre-departure tests.
A ministry official said on Tuesday that eight of the nine positive crew members were showing symptoms, but they were well enough to remain aboard the ship.