At least 100 children aged between five and 14 have tested positive for Covid-19 in the last two weeks.
According to Professor Philip Nolan, who is Chair of NPHET's Epidemiological Modelling Advisory Group, clusters will occur when schools reopen, but it is likely that they will be initiated at home.
He said he understands that it is a very worrying and difficult time for parents and teachers, but added that there is not a lot of evidence across the glove to suggests that schools are a major site of transmission.
While he admitted children will and can get the disease, they are more likely to contract it at home than in schools.
Speaking on RTE's This Week, he said: "We will see cases in students and cases in teachers and clusters in schools, but when we see that, we need to think carefully and look carefully, because it remains unlikely when we see that.
"If, for instance, there are two children in the same school with Covid in two months' time, it is much more likely that those two kids have separately got it within their own households, rather than transmitting from child to child within the school."
He said that the core advice from NPHET was for adults to stop congregating in large gatherings, saying this is the biggest concern of health experts.
He added that everyone knows the difference between a crowded setting and a carefully socially distant classroom setting.
Mr Nolan was speaking after Ireland recorded two further deaths and 156 new cases on Saturday.
