People have been asked to not hold events such as communion and christening parties in households for the next few weeks.
It comes after 84 cases of COVID-19 were confirmed by health officials this evening, with three further deaths.
NPHET will meet tomorrow to discuss the ongoing rise in cases, especially in Dublin and Limerick.
Acting Chief Medical Officer Dr Ronan Glynn this evening said he's 'very concerned' with the current situation in Dublin in particular.
He said: "It's a significant volume of disease. It isn't limited to any one setting, like we've seen in other counties previously.
"That said, it is largely linked - from what we can see - to household and inter-household transmission.
"From that perspective, there's a positive message: which is that it remains within the hands of individuals, families, communities to stop this getting worse.
"Household gatherings, communion parties, christenings, other family events where people are coming together from multiple different households: if at all possible, those need to be stopped for the next couple of weeks."
Currently, the virus reproductive number in Dublin is said to be around 1.4 - compared to around 1 for the rest of the country.
Cases are spread all across the country, with only the Dublin South region said to have a similar incidence rate to the rest of the country.
Dr Glynn said the other parts of the county all have a rate of 60.0 cases per 100,000 or greater, compared to a rate of just under 40.0 for the country as a whole.