The plan at the moment is to put Secondary children in year group bubbles so approximately 200 pupils bubbled together. If one gets ill, all the whole year group have to self isolate.
Why can't they teach in form groups of 30 instead. Where there are timetabled option subjects, teachers could supervise the work set (like prep in boarding schools). This would limit the spread significantly more. And abandon option subjects for the coming year 9s for the moment and begin GCSE subjects in form groups with increased differentiation.