Unions representing teachers have welcomed the Cabinet decision to keep primary and secondary schools closed until 11 January.
The measures are being introduced under plans to tackle the increasing spread of Covid-19.
Primary and secondary schools had been due to reopen on Wednesday 6 January. Childcare facilities and créches are not affected by the decision.
Reacting to the announcement, the General Secretary of the Association of Secondary Teachers in Ireland said the association wants people to be able to go back to school in a situation where students' and teachers' safety is assured.
Speaking to RTÉ's Drivetime, Kieran Christie said the level of relative safety that was in existence between September and Christmas needs to be maintained, and if any additional measures are needed to ensure that safety, then they are put in place before schools reopen.
He said the ASTI wrote to the Minister for Education to consult with NPHET over the new UK variant in schools, saying it was a "new ingredient in the mix" and needed to be considered in the context of safety in schools.
Mr Christie said the ASTI is hopeful that the extension to the school holidays will be used to ensure that schools are safe to return to for staff and students.
He said that the new variant needed to be considered "in a calm and measured way", and that the Government seems intent on proceeding in such a fashion.
The decision has also been welcomed by the Irish National Teachers' Organisation.
The INTO had written to the Minister for Education calling for a delay to the start of the next school term until Monday 11 January, "at the earliest".
In a statement this evening, INTO General Secretary John Boyle said: "As we set out yesterday, the alarming public health data and concerns expressed in respect of the new Covid-19 variation warrant this approach.
Mr Boyle added: "We will seek to work constructively with the Department of Education and NPHET to ensure our schools reopen next month and have the necessary supports and protection to stay open safely."
Sinn Féin education spokesperson Donnchadh Ó Laoghaire has called on the Government to use the extra time to clarify to parents, teachers and students how schools can reopen safely, and to deliver a roadmap to do so.
In a statement, he said we need to use the next 12 days "to do all we can to try to address very significant concerns".
He said parents will now fear a repeat of the situation during the first wave when schools were closed for months.
