The only contacts being isolated, tested and monitored are the 16 students who were with the case at a party on Friday night, principal Ivan Davis said.
The school had been advised from the director of education that it could stay open because the risk of Covid-19 transmission within school settings was considered low.
Meanwhile, Onehunga High School was closed yesterday and today after a student returned a positive result for the virus on Saturday.
In a notice to parents and staff, the school said the student involved was at school last week on Monday and Tuesday while infectious.
The school said "through an abundance of caution" it was asking senior students to study at home to give them time to contact close or casual plus contacts and allow for time for testing to be carried out.
Meanwhile, a teacher at Auckland's Sacred Heart College also tested positive for Covid after teaching two classes on November 5 while potentially infectious.
Only one student is considered a close contact of the teacher because the other 30 students in his classes were already fully vaccinated. The student who is a close contact had only had one dose of the Pfizer vaccine.