The HSE have circulated the following advice/guidance to schools. It is very important that your child not attend school if showing symptoms of Covid 19.
If your child does not have symptoms, even if they are a close contact of another in school or at sporting activity, they may attend school.
If your child is unvaccinated and a close contact within the household, they must restrict their movements.
If your child is a close contact of a household case and is fully vaccinated, they may attend school (presumably children over 12).