A school in Dublin says the issue of staffing is at 'crisis point' after receiving one application for a teaching job they advertised.
It comes as schools are back from the mid-term break on Monday, amid concerns following a surge in COVID-19 cases.
Paula Juliet is principal of the Thornleigh Educate Together primary school in Swords.
She told Newstalk Breakfast their options are very limited.
"We're always enthusiastic, so we're hoping we'll do our best to give the children the education they deserve.
"But unfortunately it's really tricky at the moment in relation to COVID... and also in relation to substitute teachers.
"Just to let you know: last month we advertised a job - a fixed-term temporary job - which would normally get a lot of applications.
"And we had one application for that job."
She also says colleagues have advertised a total of seven jobs and had no applications.
"It's at crisis point at this point".
'Children are missing out'
She says while they "never" use SNAs to teach regular classes, they have had to use support teachers for this.
"We have to use those teachers, because otherwise you would have to send school home.
"So you have to look at the greater good and be pragmatic and practical about what you do.
"But unfortunately those children are missing out, and with having been online over the last two years they've also missed out.
"So yeah it's a huge problem - leading into that problem is normally we can take teachers who are currently training, and at the moment they're all out on school placement.
"So we can't even take from that pool".
She says they are "extremely worried" about having to send children home as result of staff shortages.
But she adds: "That would only happen absolutely as a very, very last resort - and then that would have to be an executive decision that would be made with the board of management".
Ms Juliet says they "absolutely" want the resumption of contact tracing in schools.
"We feel like we've been thrown under the bus with regard to this".
While another Educate Together principal has said Ireland is 'haemorrhaging' teachers to other countries, after making the profession less attractive.
Simon Lewis, principal of a Carlow Educate Together school, told Newstalk: "I think it's been going on since at least 2014, it's reached crisis levels in 2016, it was only admitted in the Dáil in 2018 by Richard Bruton.
"But nothing has been done to solve the problem.
"We're haemorrhaging qualified teachers out to country's in the Middle East - we've made teaching a less attractive position than it was maybe when I started.
"This is the chickens coming home to roost - unfortunately - and we're no closer... to a solution".
And he said his school, which educates over 400 pupils, did not have one day of term with a full cohort of staff.