Anyone who attended Papatoetoe High School last week - be it staff, students or visitors - is being asked to get a Covid-19 test after a Year 9 student has been confirmed as one of three new cases.
The other two cases are the student's mother and father.
Health officials have confirmed the girl was infectious while she was at school earlier in the week and her classmates and teachers are now being asked to get tested and self-isolate until February 24.
Relatives of those classmates and teachers are also being asked to get tested and stay at home until receiving a negative result.
The school will be closed tomorrow and Tuesday.
Principal Vaughan Couillault said the infected student was only at school for one day last week, on Wednesday.
She stayed at home on Thursday and Friday after her mother, an employee at airline catering provider LSG Sky Chefs, became unwell.
Couillault said the student did not attend "any assemblies or anything like that" on Wednesday.
"So in terms of identification, we have probably the smallest numbers of teachers and students that we could have for a Year 9 student," he said.
He said five teachers and 28 students are considered close contacts of the infected student and all other students and staff at the school are "casual" contacts.
Couillault has notified all staff and parents by text and email this afternoon.
An Auckland Regional Public Health spokesperson said letters will be emailed today to all staff members and to families with students with advice on what to do.
The letters will advise staff and parents of students whether the student or staff member is a "close contact" or a "casual contact".
Auckland Regional Public Health Service defines "close contact" as someone who has been in the same class or room as the infected student.
"Casual contact" means the person is at a lower risk of developing the disease because they have not been in the same class or room as the student.
Casual contacts are being asked to get tested and remain at home until they get a negative test result while close contacts are asked to get tested and stay home until February 24.
People at the school have been told to look out for Covid-19 symptoms, such as new or worsening cough, fever, sore throat, temporary loss of smell or taste, difficulty breathing
and runny nose.
A mobile testing centre will be set up at the school on Monday and a list of testing sites is available on the Auckland Regional Public Health Service website.
The girl and her parents have been moved into quarantine after testing positive last night.
The father is a self-employed tradesman.
A list of 17 locations of interest visited by the trio have been released by the Ministry of Health this evening.
They include fast food outlets, supermarkets, hardware stores and a motel.