they should file the report оn a need-to-know-basis?

For instance, if a student has a confidential file, only the teachers, staff, and administrators who need to know the information in order to service the student would have access to the information in that file. Teachers who are curious but who do not need the information in order to service the student would not be allowed to see the file (for instance, a student who is HIV posititive: the school nurse would need this information and would have access to it, other teachers and staff do not need to know this and would not have access to this information. This a privacy concern and is why teachers and staff have been trained on how to help all students without coming in contact with bodily fluids.)

In general…consider the information being protected….

is it about a student? ‘student confidential’ might be appropriate – they filed a student confidential report

about another staff member? ‘personnel related’ always works well to imply additional protection – the report was personnel related

sorry, questions a bit vague for better answer