Whanganui Collegiate has confirmed there is one case of Covid-19 in its community.
The case is a member of the teaching staff.
"The staff member was last at school for Saturday classes and has not been at school this week," Headmaster Wayne Brown said on Tuesday evening.
"They and the students in their classes followed protocols and therefore, as advised by the Ministry of Health [on Tuesday] evening, we have no close contacts.
"With only one case, Whanganui Collegiate School will continue to operate in both its day and boarding school environments.