The child was last at school on Tuesday but is now self-isolating at home with their family.
The Manukau Institute of Technology and Glamorgan cases are among the 17 cases of community transmission, but it is unclear if the further two cases in Māngere East have already been announced by the Ministry of Health.
The school will be fully closed to all staff and students, including those of essential workers, until at least Monday.
"There will be a great deal of concern in the school community, but the child did not have the symptoms while at school," the letter said.
"This means there is a lower risk of the illness having been passed to other students."
ARPHS has said the school might remain closed for longer if other cases are confirmed there.
ARPHS is now working with the school to identify close contacts, including any classmates and staff.
Parents are being asked to keep all children at home in isolation until they receive notification from ARPHS about what to do next.
Meanwhile, Warehouse Group staff have been told someone who tested positive had visited two Noel Leeming stores at the weekend.
Auckland's Albany and Wairau Park click and collect sites were closed on Thursday and staff were asked to stay home at the request of management.
"Asking these team members to stay home was a proactive precautionary measure only. This approach is supported by the Regional Public Health Service," staff were told in an email.
The Warehouse Group has been contacted for comment.
Auckland public health officials said Southern Cross Campus and Taeaofou I Puaseisei Preschool in Māngere East have been closed after cases were confirmed there.
ARPHS is working to identify close contacts of the confirmed cases. A spokesperson said staff and families had been advised to continue adhering to Auckland's alert level 3 restrictions, and stay in self-isolation until they hear from the service with advice on what to do next.
The MIT student, who was studying in TechPark's general engineering area based at South Campus, Ōtara, was not on campus while they were infectious, students were told.
The student is in self-isolation and will not be attending classes until they have recovered from the virus.
Manukau Institute of Technology campus in Manukau. Photo/ Nick Reed
No students or staff have been deemed to be "close contacts" of the positive case.
"While there may be some concern in the MIT community, please be assured that it is very unlikely the person spread the virus on campus before becoming sick," students were told in an email.
"The campus buildings are considered safe and there is very low risk to anyone else at the Institute."
Thirteen new cases of community transmission were announced yesterday, all linked to the same Auckland cluster - the four people who were reported as confirmed cases yesterday and the day before.
Director general of Health Ashley Bloomfield said 17 of the total 36 active cases in New Zealand were linked to the new outbreak.
"Given that all these cases are linked, we are treating them as a cluster."
The new cases include other children. One is a girl aged 1 to 4 while the other is a boy between the ages of 5 and 9. Another girl who tested positive is aged between 10 and 14, while a teenage male (age from 15-19) is among the new cases.
Meanwhile MIT campus remains closed under level 3 restrictions.
Students were urged to remain alert to symptoms of Covid-19, including a new or worsening cough, a sore throat, runny nose, fever, a temporary loss of smell and difficulty breathing.
"Finally, if you know the identity of the student with Covid-19, please do not disclose their names or details to anyone else," the polytechnic urged.
