The principal of a Co Down grammar school said having to telephone 17 families to tell their daughters to self-isolate was a "horrible" experience, but one which could have easily been avoided.
It is a scenario that has been played out at hundreds of schools across Northern Ireland in the last few days as schools remained open.
Fiona McAlinden, principal at Our Lady's Grammar in Newry, said the experience has left her "frustrated" and it would never have happened if school principals had been listened to by the Education Minister. She explained how a pupil tested positive on Friday, the final day before closing for Christmas. She said there have been five cases at the school since Halloween, which are not related.