Around 100 people at Mt Albert Grammar School in Auckland have been identified as close contacts of a student infected with Covid-19.
The student was a close contact of a family where four members have the virus in South Auckland.
Auckland Regional Public Health (ARPH) says students and teachers in five classes the infected student attended on Monday have been told to self-isolate as they are close contacts.
The student wasn't symptomatic on Monday, but fell ill later and tested positive yesterday.
ARPH says there is low risk to others in the school community.
"We have been able to identify the students most at risk, in the student’s classes and they have all been advised to stay at home in self isolation for 14 days", says Headmaster Patrick Drumm.
"Because of privacy concerns, the school will not be telling parents or staff the name of the student who is a close contact, their class or year level."
One Mt Albert Grammar parent received the email last night. She told 1 NEWS she was informed of the case, and was told she would be contacted again if her family was implicated as a close contact - which it wasn't.
She said the case confirmation "is what it is" and there is "no point in panicking" about the outbreak.
"We just have to carry on, we've already done our school work for today so get some fresh air and isolate and just be mindful of people."
The Director-General of Health Dr Ashley Bloomfield told TVNZ1's Breakfast this morning the school community had been notified last night.
He said more cases derived from the family would "almost certainly" arise.