The Government has recommended that all teachers and secondary school students wear face coverings when a physical distance of two metres cannot be maintained.
The updated recommendations were published by the Department of Education following engagement with teachers, principals, and other key education stakeholders.
The updated advice was provided by the Health Protection Surveillance Centre.
The department has confirmed that face coverings should be worn by all teachers in both primary and secondary schools, where a two-metre social distance cannot be maintained.
Minister for Education Norma Foley said she had been working with the public health authorities to ensure that the advice underpinning the safe reopening of schools is fully up to date.
The Department of Education said that schools have been provided with a Covid-19 specific capitation grant to support greater cleaning regimes in schools.
It said that the payment is intended to allow for an extra four to six hours of cleaning in schools per day.
The department says that more Covid-19 rates are payable "in respect of students attending special schools and special classes attached to mainstream schools in order to assist with the extra costs arising from the cleaning of classrooms operating specialist provision".
Last week, the Government announced its €375 million school reopening plan.
Teachers' unions have welcomed the updated advice.
The Association of Secondary Teachers, Ireland said it had written to the minister last week seeking a review of the interim advice ahead of schools reopening in late August.
ASTI General Secretary Kieran Christie said: "Schools are working hard to implement the necessary safety arrangements in time for reopening.
"Keeping schools open must be the priority, and this means minimising the risk of transmission within classrooms and other learning environments."
The Teachers' Union of Ireland said it had discussed with the department the growing acceptance across society that the wearing of face coverings is a prudent protective measure.
TUI President Martin Marjoram said: "The union has consistently called for publication of this guidance as early as possible so that schools can plan accordingly and procure the required equipment.
"It is now vital that the required resources are provided to schools to ensure that this crucial protective measure is in place when schools reopen.
"The health and safety of students, staff, their families and communities must remain the key concern for all and the TUI, therefore, will continue to address any arising issues with the department ahead of the reopening of schools."
Trade union Forsa which represents special needs assistants, school secretaries and caretakers, has said the new guidelines will maximise the Covid-19 protections for staff like SNAs who, unlike most teachers, will be unable to maintain social distancing.— Sharon Lynch (@sharonmlynch) August 7, 2020
Meanwhile, the Teaching Council has said that it is introducing a number of measures to support teaching and school communities as schools reopen for the new academic year.
It said that the measures focus on increasing the supply of registered teachers who are available to fill vacancies, including supervision and substitution roles.
Separately, Taoiseach Micheál Martin has announced the reimposition of restrictions for two weeks in counties Kildare, Laois and Offaly in response to an increase in the number of cases of the Covid-19 virus in the region.
Acting Chief Medical Officer Dr Ronan Glynn has advised people living in those counties to pay particular attention to any new symptoms after a huge increase in Covid-19 cases linked to outbreaks.