Public health teams will be available around the country to fast-track the testing of suspected cases of Covid-19 that emerge in schools.
Depending on the time of day, swab results could be back within 24 hours or, if not, within 48.
It is one of the measures being developed to tackle the virus threat as up to one million pupils and 100,000 staff return to classrooms for the first time since March.
Guidance has been issued to schools about the steps to follow and what will happen if a pupil or staff member is a suspected or confirmed case.
The "Schools Pathway for Covid-19, the Public Health" has been developed by the Department of Health, led by Dr Ronan Glynn, the HSE and the Department of Education.
It says it is inevitable that, with confirmed cases of Covid-19 within the community, there will be suspected or confirmed cases in schools.
Infection transmission within school is regarded as low risk once measures such as social distancing and hand washing are followed.
It is considered more likely pupils or staff would bring the virus into school from home.
Where Covid-19 is confirmed in a school, each case will be assessed individually to decide on what follow-up action is needed. The guidance says every school is unique and the risks will be unique too.
Public health experts will decide on who else needs to be tested and, in the event of an outbreak - two or more cases - will decide whether to close a school or exclude a class or a smaller group, such as a pod .
If a pupil is removed from school with symptoms of concern, parents will have to discuss the matter with their GP, who will decide if a test is needed.
Symptoms of concern and/or symptoms consistent with Covid-19 include fever or a new cough, shortness of breath, deterioration of existing respiratory condition or loss of taste or altered sense of taste.
If the test is positive, the HSE - not the school - will follow up with contact tracing of close contacts and a risk assessment. Under public health guidelines, close contacts will have to quarantine for 14 days.
According to the guidance, the definition of close contacts within schools will be variable.
It will not be automatically assumed an entire class will be deemed close contacts.
It explains this is because the schools are so varied.
In young primary school children, pods - small groups within a classroom - will likely be deemed close contacts and all members will be removed from school.
In second-level schools, where there is social distancing rather than a pod, close contacts will be determined by proximity and interaction with the confirmed case.
Factors taken into account in determining close contacts in second-level schools will include classroom structure, travel and friendship groups.
If the GP decides a child needs to be tested, they then become a suspected case and, at that point, siblings or other household members should also be removed from the school until the test result is received.
The guidance also points out children will also continue to display symptoms of other circulating respiratory viruses and refers to the prevalence of a persistent cold among children.
It advises that children with a blocked or runny nose but no fever can attend school, but if they require paracetamol or ibuprofen they must stay at home for 48 hours and the parents should phone the GP to assess if a test is needed.
Meanwhile, the Department of Education has confirmed it is still obliged under law to inform Tusla when a child has missed more than 20 days in the school year.
A spokesperson said it will take into account "the requirement for students who feel unwell with symptoms consistent with Covid-19 or who have been informed to self-isolate, not to attend school".
Under the Education Welfare Act, schools are legally required to inform relevant authorities about high absenteeism levels.
There are fears absent rates may be higher in schools in the 2020/2021 academic year as a result of the coronavirus pandemic.