The warning comes ahead of the Government's €300 million plan to reopen schools by the end of August, which will be launched later today.
Primary school students are set to be sectioned off into pods of between four and six children.
Strict cleaning regimes, investment in school buildings and more substitute teachers are also expected to be included in the plans.
President of the Association of Secondary Teachers in Ireland, Deirdre McDonald, says the plan has to be safe:
“We know that these are the things that we have sought, we have fought a valiant battle to make sure that our members and our students will be returning to a safe environment.
So we do hope that what is necessary will be put in place, if it’s not – well we won’t be back, the students won’t be back, because it would not be safe.
Principal of Colaiste Éamann Rís in Cork, Aaron Wolfe, says the Government’s plan needs to be realistic:
“That it’s not kind of the work of fantasy, and that these things can happen within five weeks because we’re going back to school around the 25th of August.
I know principals up and down the country, and teachers as well, are extremely worried, and hope that all these things can be put in place for the return to school.”