The primary school system is 'creaking at the seams' according to the Irish National Teachers Organisation.
A survey of around a quarter of primary schools has found that 605 teachers were Covid-positive in the first two weeks in November.
In almost a third of instances, principals could not find cover for an absent teacher.
INTO General Secretary, John Boyle, is calling for mass testing in schools to be reintroduced.
"The danger here is that whilst there's 9,000 children in the last fortnight with Covid is that there could be 13,000-14,000 with Covid in schools who are asymptomatic.
"There was a way of finding out those things up to the 27th of September, but those supports were stripped out.
"We believe that a lot of the supports have to be reinstated."
