The new Covid-19 community case identified this morning is a Papatoetoe High School student who was tested for the first time yesterday.

The schoolgirl was identified as a casual plus contact of the community cases linked to the February outbreak but had not returned to the school and had been isolating at home, Covid-19 Response Minister Chris Hipkins said.

The student lives in a house with six people, including one family member who also goes to Papatoetoe High School.

That sibling has not been back to school either.

Director General of Health Ashley Bloomfield said all of the family members of the new case are being tested but only the confirmed case is symptomatic at the moment.

"We are working as fast as possible to gather all the information we can."

All students at Papatoetoe High School were asked to be tested after the outbreak was discovered on February 14.

But he said there had been "a lot" of attempts to contact the family from the Public Health unit's contact tracers.

The latest case was only able to be tested yesterday, Bloomfield said.

The student had some symptoms and reported loss of smell and taste yesterday.

She was tested at a community testing station.

Bloomfield said the Ministry of Health "simply does not have" any information about whether the student was adhering to self-isolation rules.

He said that information will be confirmed soon, after interviews with the family.

"It's important that we let this investigation take its course," Hipkins said.

Papatoetoe High School principal Vaughan Couillault said all students and teachers are being re-tested immediately, with four stations in the hall testing people already.

"There's a huge squad that turned up in about 45 minutes and we're rolling.

"At this point we are starting with senior students and working our way down because of the nature of the positive case and the interviews."

He said the idea is to test as many students as they can today, because they're already there.

"It only takes a few minutes and there's a few testing stations so they're really trying to crank through as much as they can," Couillault said.

Couillault said people were "disappointed" and "frustrated" they were going through this again.

"But I'm very confident that everybody will revert back and get the job done like they did last time."

In the meantime the school would close this evening until further notice, a post on the school's Facebook page said.

Students and staff who got tested before Monday February 22 were being asked to get tested again and everyone linked to the school community including family members of staff and students must isolate until all the students or staff members in their household had a negative test result.

Hipkins said the "vast bulk" of students at Papatoetoe High school had been tested after the Valentine's Day outbreak, but there were seven people still to return a negative test, including the Covid-19 positive student announced today.

All of these students are "being followed up".

"We want to find them all, and test them," Bloomfield said.

He said from some of the families, there have been up to 12 phone calls to get them to be tested.

Sometimes, there is a language barrier, Bloomfield said.

"It just takes some time to get hold of someone," Hipkins said.

He said in his experience, the last handful of people take the longest.

"The tail is being chased up now," Bloomfield said.

But overwhelmingly, New Zealanders are "trying to do the right thing", Hipkins said.

He called on people to not pass judgment on people who are taking a little bit longer to get a test.

Bloomfield said he does not think the case announced today is from a new strain. Rather, it's highly likely to be linked to the Valentines Day cluster.

Hipkins said Papatoetoe High School has stayed in a level "more akin to level 3" since the outbreak and all teachers and students were required to stay home until they got a negative result for their Covid-19 test.

Hipkins is asking all students and teachers to be re-tested at the school, while household members can be tested at a nearby community testing station.

Papatoetoe High School's website says it has 1500 students and more than 150 teaching and non-teaching staff.

Bloomfield said asking for a second test was just a way that officials can be sure there are no other cases.

"The virus does tend to have a long tail," Bloomfield said.

All family members of any students at Papatoetoe High School are being asked to self-isolate until the student returns a negative test.

He said wastewater testing has shown negative results in the Papatoetoe area.

There have been 70,000 tests which show there is no community transmission.

The Valentines day cluster is now at nine people, Hipkins said.

Bloomfield said that "every individual has a different response to the virus" and people who don't have respiratory symptoms like coughing and sneezing are much less likely to spread the virus to others.

There are still another 10 students who are considered casual plus - they are being followed up with, Bloomfield said.

A casual plus contact is a person who has visited a location of interest at the same time as a person who has since tested positive for Covid-19, but does not meet the criteria for a close contact.

There are 27 locations of interest connected to the latest outbreak in the Papatoetoe area and 1416 casual plus contacts identified.

Of those contacts, 1402 had returned negative tests and yesterday the Ministry of Health said there were 13 results outstanding.

The official advice for anyone who has been identified as a casual plus contact is advised to stay home, get a test and to call Healthline.

In addition to the case today, there are five new cases in managed isolation.

So far the Auckland cluster has involved two family groups.

The first cases, a mum and teenage daughter, tested positive on February 13. A day later the father tested positive.

The second family at the heart of the cluster involved a classmate of the teenage girl from the first family. She tested positive on February 16 went on to infect her older brother, also a high school pupil, and her mum and dad. Another teenage girl in the family tested positive on February 21.

Hipkins on Australian woman refusing Covid test in MIQ

Asked about the Aussie woman who is refusing a Covid test, he said if she gets a clean bill of health and is Covid free, she would be able to leave after 28 days.

"It's a stay that's twice as long as it needed to be."

He said he was not considering deporting her "at this point".

He could not say if she was paying for the extended stay, or if it was taxpayers.

Hipkins said it is up to everyone individually if they want to get a test.

"It's unfortunate when people buy into conspiracy theories," Hipkins said.

"Especially, he continued, "when it's something as important as Covid-19."

Source of Valentine's Day cluster

Mystery still surrounds the cause of the outbreak. The ministry said the Auckland Airport precinct where the woman at the start of the February cluster worked remained "the most likely source of the outbreak", but further testing had not identified any potential transmission routes.

All scenarios for possible infection sources of the Auckland February cases continue to be thoroughly investigated.

ESR has been reviewing all B.1.1.7 strains identified over the last two months to see if there was any possible link to the latest case.

An Auckland managed isolation facility was the focus of investigations with a possible genomic similarity identified between a previous covid-positive person.

All in the Four Points by Sheraton facility in late December were now being retested. Of the 265 returnees, 36 had since gone overseas and seven of the 229 in New Zealand were proving difficult to contact.