Nine crew on a containership off New Zealand are infected with the Delta variant of coronavirus, according to authorities.

The 4,363-teu Mattina (built 2007) arrived at the country's South Port on Sunday with two seafarers initially testing positive for the virus.

Seven more of the vessel's remaining 19 seafarers also subsequently returned positive tests.

“Results of whole genome sequencing from nine crew members of the Mattina show they have the Delta variant of Covid-19,” the New Zealand government said.

“All crew who have tested positive will remain quarantined on board the vessel at this time, where they will maintain the minimum functions at the port. They will not have direct contact with any port staff while maintaining these functions.”

On a positive note, three of the crew have again returned negative results on Friday following further testing.

Quarantine facility

Plans have now been finalised to ensure the three negative seafarers, including the ship’s captain, are able to safely leave the ship and isolate from those who are positive.

New Zealand authorities said in some cases it is safer to manage the smaller group of negative cases by taking infected seafarers off the ship.

Two crew will be transported to a Christchurch-based quarantine facility using a “well-planned, securely managed transport plan, including the use of infection prevention and control protocols”.

The captain will isolate near the Mattina, as he must remain close in case of emergency, officials said.

“Transportation from the ship to quarantine for the three members who have tested Covid-19 negative will be done under strict infection prevention and control procedures, including the use of full PPE,” a government spokesman said.

“Around the clock security will be on site at the accommodation to ensure full compliance by the captain.”

If the master does need to return to the vessel, there are plans in place to handle his return in a secure way.

“These plans have been put in place to ensure the safety of the negative crew members at the same time as the health and well-being of members of the community,” the spokesman added.

The Mattina remains in quarantine in a secure area of the port, which is described as inaccessible to members of the public. Fencing has been put up to further restrict access to the ship.

The initial two crew members who tested positive for Covid-19 are said to have joined the ship in Singapore on 2 July after providing negative pre-departure tests.