In the past week, 30 new Covid-19 outbreaks have been identified in schools - while there are 125 open clusters in the settings.
Households is still the largest spreader of the disease according to the Health Protection Surveillance Centre (HPSC) with over 3,000 open clusters.
It comes as 444 new infections were reported in the Republic of Ireland, with the estimated national 14-day incidence rate falling again to 212.
The reproductive number of the disease is believed to be between 0.7 and 0.9.
Monaghan GP Illona Duffy says the key to keeping the infection rates low is stopping non-essential travel across the Border.
Ms Duffy said: "We've got to keep doing what we're doing and continue to do it well, that unfortunately means having to stay away from people, not gathering in groups, not travelling."
Speaking at last night's Nphet briefing, chief medical officer Dr Tony Holohan said that it is crucial for close contacts of confirmed Covid-19 cases to isolate for a period of 14 days and get tested.
“This is because as an identified close contact, you have come into contact with the virus. It may take some time for this to become apparent, or for you to become infectious.
“In following this important guidance, you are helping to bring this virus right back down to where we all need it to be and playing your part in this national effort.”
