"Pilots were required to board vessels of this size when berthing. The pilot wore appropriate (personal protective equipment) and was fully vaccinated.
"No one else has been on or off the ship since it docked."
The testing that took place yesterday morning was carried out in the gangway area. All appropriate protocols were followed by health stuff, including PPE, the ministry said.
Exactly what will happen to the ship is not yet known, as the Southern District Health Board's health officials, alongside other agencies, work to determine the next steps for the vessel.
"In the meantime, the crew members remain on board the Mattina."
Additional fencing is also due to be put up to further restrict any access to the ship.
The Mattina, which was brought into port in Bluff on Sunday night, is the third vessel in New Zealand waters to be struck by coronavirus.
The Mattina's positive Covid results follow those reported on Spanish-flagged vessels the Viking Bay and the Playa Zahara in recent weeks.
A total of 16 of the 18 crew of the Playa Zahara last week tested positive for Covid-19.
The vessel was brought into Port Taranaki so those on board could be tested before it made its way to Lyttelton Port in Christchurch.
