Antigen testing is to be rolled out across primary schools 'as quickly as possible', the INTO says.
It follows a meeting between the union, the Department of Health and public health officials on Wednesday morning.
Details are expected to be available by this weekend, according to the general-secretary of the Irish National Teachers Organisation.
John Boyle told The Hard Shoulder something needed to be done.
"Our cries for help for the primary school children of Ireland have been heeded.
"Today there's 6,144 children of that age who have COVID-19, and they're really startling numbers.
"There had to be an intervention, doing nothing was not an option.
"They've confirmed to us now that the Chief Medical Officer has asked for this to be processed as quickly as possible.
"We don't have the detail as to how it's going to be rolled out, but we know that they're going to base it on recommendations in the ECDC.... report from last week.
"That would indicate to me that it's likely that it's going to be a programme of test-to-stay.
"In other words, you identify the close contacts of the confirmed case... and then at that point that small group, or maybe even the full class depending on the number of cases, would have to do the antigen test.
"And then obviously if they test negative, they come back to school - if they test positive they would have to go and get a PCR".
He says a middle ground will have to be found around absenteeism.
"Nobody wants to see well children being absent from school, but with those numbers of children absent at the moment it's quite chaotic for a teacher if you have so many children missing from your class.
"I don't think there's going to be screening in that sense... maybe where there's a confirmed case in the class, and then the people closest to it."
But he says the finer details are still unclear.
"I'd imagine it's either the public health people will come to the school where there's an outbreak... or else the parents maybe will bring that small group of children [sic] will go home to their families and would be done.
"And than the next step, obviously, might be that they have to go onwards to a test centre for a PCR.
"I don't envisage the teachers are going to be asked to do mass testing in the school setting".
Infectious disease specialist Professor Sam McConkey has suggested antigen testing in schools could offer false reassurance if not used correctly.
"If somebody is at a sleepover the previous night and uses an antigen test tomorrow, that is too early for the antigen test to show up as a positive.
"They don’t pick up very low levels of virus," he told Newstalk on Monday.
"You would really need to be testing at day five and day 10 and then using those results appropriately.
"So I worry that false-negative results, particularly early after a child has been in contact with somebody else with symptoms or with COVID, might falsely reassure the child and their parents," Prof McConkey added.