Form 4 pupils at Belfast Royal Academy were sent home this week after a positive case of COVID-19.
Holy Trinity College in Cookstown also closed its doors this week after a member of the school community tested positive.
B.R.A was the first school to make face coverings mandatory.
The form 4 academy year group has around 200 pupils.
The Principal Hilary Woods wrote to parents, informing them of the positive test.
She stated that ensuring the safe return of pupils and staff was her ‘absolute priority.’
At the start of term, pupils were informed that they would not be allowed to enter classrooms unless they were wearing a face covering.