Dr Graham Gault, director of school leaders' union NAHT(NI), said:

"Covid is still very prevalent across all of our schools and the reality is that the staffing crisis, which was well publicised earlier this year, is still at a critical level. Many school leaders are finding it impossible to source substitute teachers and do not have the resource available within the school to keep all classes open for all children. The inevitable impact, in many cases, is short-term closure, until safe staffing levels can be restored.

"As a result of our appeals before Christmas, DE sought additional teaching resource from retired teachers as well as from others who may be otherwise employed. The problem of staff absence is so serious, however, that it cannot possibly be wholly mitigated by any gains main through these efforts.

"Our communities need to be understanding if schools are forced into making serious decisions on the grounds of safety, and the system must remain cognisant of the realities and remember that our school leaders cannot be expected to cope with anything beyond the critical business of running a school during the pandemic."