The fourth person in New Zealand diagnosed with coronavirus attended the Tool rock concert at Spark Arena last Friday.
This man has already been in self-isolation since Wednesday and has appropriate support from health officials, Director-General of Health Ashley Bloomfield told media.
The man does not require hospital-level care.
The man was in the general admission section at last Friday's Tool concert in the front left-hand corner of Spark Arena.
"We encourage all people in the area of the concert to be aware of the symptoms and contact the Healthline if concerned," Bloomfield said.
"The advice is that the risk is very low for all others who attended this concert."
Casual contacts at the Tool concert could be in the hundreds, Bloomfield said.
"There was no way of tracking the people who were in that area of the concert, they are classed as casual contacts and the advise to them is to call Healthline if they have any symptoms. The people we are focused on tracking down the close contacts and health officials have been in touch with all those people," he said.
The Ministry of Health continues to support students and schools who have links to coronavirus patients.
A number of tests are underway including the father of the third case.
"If negative we will still consider him a probable case as he is considered the one who passed on the symptoms to case three."
"The test takes about a day to return a result. Tests taken to today will come early evening before officials are informed. Then there is a very thorough interview with the case about where they have been and else they could have possibly infected," he said.
There is no need to name the medical centres where positive results have occurred, he said.
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"We have obligations to notify WHO of every case. Healthline had another very big day yesterday and they continue to scale up their staff to cope with the demand. Reminder to reserve calls to the Healthline for health concerns only, not general coronavirus concerns."
"We want to find cases, finding cases indicates success not failure. It's fundamental to protect the community. "
Yesterday, a third person was confirmed to have contracted the disease.
A family member of the infected man – and an Aucklander in his 40s – had been in Iran and returned to New Zealand on a Qatar Airlines flight from Doha to Auckland on February 23, flight number QR0920.
"This third case of Covid-19 is classified as what we suspect is a case of family transmission," Bloomfield said.
This was the first case of person-to-person transmission inside New Zealand and Bloomfield does not expect this to be the last.
There have been 96,500 confirmed cases of Covid-19 across the world and 3330 deaths.
Meanwhile, an NZ Steel employee is one of the four Kiwis to contract coronavirus, with staff told about the confirmed case by email and in emergency meetings.
The steel manufacturer's chief executive, Gretta Stephens, told staff the company had been advised of the new case on Thursday morning.
"We are pleased to advise that the affected employee has confirmed that they are not seriously ill and are in isolation at home," Stephens wrote in an email to staff.