A national school is dealing with a suspected case of the Delta variant in Co Offaly.
Parents have been contacted by the school telling them that if they use a bus service, regardless of what class they are in, they are considered to be a close contact.
Contact tracers are to get in touch with them over the weekend.
In the meantime, parents have been told the children should isolate at home until they hear from public health.
The school also says existing cases it is dealing with in other year groups are from a different strain and unlikely to be connected.
HSE Chief Paul Reid said today that there is an enhanced tracing process in place where a case of the variant is detected.
"In some cases where we might not deem a person as being a close contact, if it was the case of a variant, we would deem a lot more people close contacts," he said.
According to the National Virus Reference Laboratory, there are 139 confirmed cases of the Delta variant in Ireland, up from 126 last week.
The majority of these cases are located in Dublin.
The Delta variant has been found to double the risk of hospitalisation compared to other variants.
This evening, Nphet reported 313 confirmed Covid-19 cases in Ireland.
The latest figures show there are 53 Covid patients in hospital, of which 15 are in ICU.