Auckland's Marist College now has five confirmed cases of coronavirus, up one from yesterday.
Director-General of Health Dr Ashley Bloomfield said staff and students from that college should not have contact with other people, and they should also keep their distance from people in their own households.
The decile 7 Catholic girls' school with 759 students in Mt Albert has been closed all week after a teacher tested positive for the virus at the weekend.
Other staff and students at the school have been tested and principal Raechelle Taulu said this afternoon that she was still waiting for her own test results.
Auckland Catholic Diocese Vicar for Education Catherine Ryan said all schools in the Auckland Central Catholic Schools Kāhui Ako (Community of Learning) were contacted by the Ministry of Health because the Marist teacher who initially tested positive had attended a conference of the group.
But she said the Ministry of Education told the schools yesterday that health officials had determined that the Marist teacher was not infectious when he or she attended the conference, so there was "very little risk to the other attendees at the conference from this person".
"Schools are following the advice and guidelines of the Ministry of Health," she said.
Taulu told parents in a newsletter yesterday that all staff and students at the college were considered "close contacts" of the teacher who first contracted the virus.
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"This means that families need to assume that their daughter has been in contact with a teacher or student that has Covid-19," she said. "However, this does not mean that your get the virus, but we have a duty of care to inform you."
• Lockdown information: covid19.govt.nz