More than 80 students and staff from a Waikato school are isolating after a student tested positive for Covid-19

The school is one of two in the region to learn they have a positive case this long weekend.

Hamilton Christian School Principal Shaun Brooker says he's disappointed for all the families who have had to return home and isolate.

Up to 50 additional students and staff would be considered to be secondary contacts, and officials are still working to determine who they are.

Meanwhile, it's been confirmed a Covid-19-infected person was at Rototuna Junior and Senior High School for two days last week.