One of the country's major teachers' unions has called on the Government to delay the reopening of schools.
The INTO says an "alarming" increase in COVID-19 cases means schools shouldn't reopen until at least January 11th.
Schools are currently set to reopen on January 6th.
However, the INTO has written to Education Minister Norma Foley saying "the ability of schools to operate normally is likely to be seriously impaired due to the higher numbers of staff and students who will need to self-isolate and/or restrict movement in the weeks following Christmas".
It comes as the Cabinet is due to meet today to consider advice from NPHET amid the high rates of coronavirus in the country.
NPHET has recommended the introduction of full level five lockdown measures, including the closure of non-essential retail.
More than 1,500 new cases were confirmed yesterday - the highest in a single day since the pandemic began.
The number of COVID-19 patients in hospitals, meanwhile, has risen above 400 for the first time since May.
Hospital numbers have risen rapidly, and the current number is nearly double the figure recorded just a week ago.
'Consider delaying the start of the next school term '
In a letter to Minister Foley, INTO General Secretary John Boyle said nearly 700 children of primary school age tested positive for COVID-19 in the 14 days before the Christmas holidays.
He also raised concerns around the new strain of COVID-19, which has been detected in Ireland.
Mr Boyle said: "Our measured proposal to delay the commencement of the Spring term by a minimum of three school days is designed to minimise disruption to pupils and their families, while providing schools with much needed time to put enhanced safety measures and supports in place.
"In our view your government would also be better placed late next week to take account of emerging scientific evidence regarding the new variants of COVID-19 than you possibly could be within the next seven days."
Ministers will meet later today to discuss the coronavirus situation in the country.
Speaking yesterday, Health Minister Stephen Donnelly said the Government was not considering closing schools.
He said: "We will be meeting to consider new measures: it's an unscheduled Cabinet meeting and we are meeting specifically in the context of the NPHET advice which is to move to full level five and indeed the rise in cases and hospitalisations.
"But suffice to say the purpose of the meeting is to look at the measures and see are there more changes required given the situation we're facing."
While Ireland is currently in 'level five' of restrictions, there are currently a number of 'adjustments' - with the likes of non-essential retail and gyms allowed remain open.
However, the 'full' level five restrictions allow schools to remain open.
