Our new Covid-19 case didn't share any classes with other infected students at Papatoetoe High.
The latest case was tested yesterday and hadn't returned to the school when it reopened on Monday.
The Ministry of Health's now requiring everyone in the school community, including all household members, to stay at home until they return a negative test.
Covid-19 response minister Chris Hipkins told Heather du Plessis-Allan officials will be looking at where the cases' paths crossed.
"Could they have come into contact with each other on a change between classes, so were they in the same classroom, even if it wasn't the same class?"
Hipkins says they've got people driving round to track down the last handful of students who haven't yet been tested.
He says she was one of a handful of people who needed to get tested, but were difficult to get hold of.
"I don't have a detailed explanation for why it took so long for this person to get a test.
"I do want to say it's easy to pass judgement when we don't have all the facts."
Hipkins says there's now only a few people from the school who they're tracking down.
He denied rumours there are more cases in the community, saying he has not been informed of any beyond the current case.
Meanwhile, experts are confident Auckland still faces a low risk of community outbreak, despite today's latest Covid-19 case being a "casual plus" contact.
"The good news is that the new case and her sibling have not been back to school since this outbreak started, so the risk to the community is still fairly low," Covid-19 modeller Professor Michael Plank said.
"The important thing now will be for contact tracers to track down any close and casual contacts the student and her household bubble may have had over the last few days, and for them to get tested."
Otago University epidemiologist Michael Baker was similarly optimistic.
"This [latest case] was someone they were intending to check out anyway, and they just missed them," he said.
"It shows the system is working - and how hard it is to track down every last contact, when you have over 1000 of them."
Asked whether the involvement of the more-transmissible UK variant could partly explain why the case was only a casual-plus contact, Baker said it was difficult to speculate.
Even with the strain, he added, how the virus spread was dependent on individual factors.
"And it's worth remembering that it took a great deal of observational data to conclude that these variants were more transmissible," he said.
"Overall, I think this pattern is still manageable, because, while this is what happens with a larger cluster than usual, it is still consistent with the idea that contact tracing, and looking at concentric circles of contacts, is effective.