The coronavirus in New Zealand has spread beyond four members of a south Auckland family and infected a high school student.

Mount Albert Grammar School was informed of the positive case on Wednesday night, principal Patrick Drumm told NZ Herald.

“We have already notified the students and staff who are considered close contacts,” Mr Drumm said in a letter to parents.

 “We are offering support to both the student and their family and we request their privacy is respected at this time.”

The infection comes as Auckland returned to lockdown and New Zealand’s “rapid response” contact tracing swung into gear in a mad dash to contain the country’s first COVID-19 outbreak in three months.

Eight cases of the deadly virus have been identified in Auckland – four confirmed and four probable – linked to one family.

It is unclear whether the high school student was the teenager referred to on Wednesday as having a probable case of coronavirus.

The other probable cases included three adults. They along with the teenager are reportedly related to the coronavirus infected South Auckland family.

New Zealand’s biggest city returned to a ‘level three’ lockdown at noon on Wednesday, shutting many businesses, schools and largely keeping 1.5 million Aucklanders at home.

Cabinet ministers will meet on Friday to make a decision on whether to extend, end, deepen or lessen the restrictions.

That meeting will also consider the country’s election date, currently set for September 19, but now under a cloud.

Auckland’s level three lockdown will initially last for 60 hours, from midday on Wednesday to midnight on Friday.

The lockdown is a sharp departure from the life Aucklanders were living for the last three months, but Prime Minister Jacinda Ardern justified the decision by pointing to the resurgence of the virus in Australia.

“There were 322 new cases of COVID-19 in Australia yesterday. 664 people are in hospitals, 54 in intensive care units and 39 on ventilators,” she said on Wednesday.

“Our response to the virus so far has worked.

“We know how to beat this. But we also know we don’t need to look far to see what it can mean if we don’t get on top of it.”

The rest of NZ has moved to ‘level two’ restrictions, which requires social distancing and caps the size of gatherings.

Aged care homes have moved to the strict ‘level four’ in a precautionary move; most of New Zealand’s 22 deaths from COVID-19 have taken place at rest homes.

As part of the response, Aucklanders are being asked to wear a mask for the first time through the pandemic – though Ms Ardern is yet to make it mandatory.

“Think of it as a duty to one another. It’s a proven line of defence … it’s also a sign you care about your community and our team of five million,” she said.

Five million masks will be handed out, and Air NZ has asked passengers leaving Auckland to wear masks on their flights.

-with AAP