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.
"We have appropriate public health measures and cleaning procedures in place."
Brown said the school would be guided by the Ministry of Health and the Ministry of Education.
"This is a situation which we have been preparing for and I am pleased with how staff are enacting our protocols.
"In speaking with the Ministry of Education this evening, they commented on the exceptional actions of the staff member involved."
School families were notified on Tuesday evening.
Brown said having a confirmed case was not a reason for panic or anxiety but people should watch for symptoms and any developed, to get tested immediately.
"What is important now is that we continue to care for everyone in our community."
Earlier on Tuesday, the Ministry of Health confirmed 19 new cases of Covid-19 in the Whanganui District Health Board region, bringing the number of active cases to 65.
There were 2846 new cases of Covid-19 across New Zealand on Tuesday.