A 'challenging' level of COVID-19 cases in January is 'more likely than not', Dr Tony Holohan has warned.
NPHET believes the daily case numbers have hit a low point, and will fall no further this side of Christmas.
Increased socialising over the Christmas period is also expected to lead to an increase in coronavirus transmission.
Today saw a further 242 cases of the virus confirmed in the Republic, with the 14-day incidence rate now at 80 per 100,000.
While both the 14-day and 7-day incidence rate are the lowest in Europe, the latter is 'ticking upwards'.
Speaking this evening, Dr Holohan said: "The five-day average now is just under 290 cases - we're bottoming out, as it were. We think we've passed the low-point.
"It's more likely than not that the level of socialisation we'll see will leave to a challenging level of transmission in the early weeks of January.
"Even though we believe there are measures we can recommend... to minimise the risk of that, if we ask ourselves honestly how likely it is that we might avert a significant surge in infection in January... we think it's probably less likely than more likely."
Dr Holohan urged people to limit the activities they choose to do over the coming weeks.
He explained: "If you go to the shops, followed by a visit to a restaurant, followed by a visit to museum, gallery or whatever takes you're fancy... if you do all those things you're going to increase your opportunity to pick up this infection."
