The chief medical officer has warned against holidaying as he revealed 7% of cases recorded in the past two weeks were linked to travel.
Dr Tony Holohan said the National Public Health Emergency Team has expressed a "clear view" that trips abroad may cause the virus to begin spreading in Ireland again.
He also noted that a number of countries in Europe have seen a rise in infections recently.
Speaking on Thursday evening, he said: "NPHET noted today that over a third of new cases in the past 14 days are under 35 years of age.
"It also noted a number of EU countries reported an increase in new cases.
“7% of cases notified in Ireland over the past fortnight have been associated with travel.
"NPHET expressed a clear view that overseas travel poses a risk to importation of the disease and to further transmission in Ireland.
“The ECDC has recently warned that the pandemic is not over. Ireland has made significant gains in suppressing COVID-19.
"Our task over the coming weeks and months is maintaining these gains.”
Dr Holohan was speaking as the death toll in the Republic rose to 1,727 following one further virus related death.
And a rise of 11 confirmed cases has brought the total number of infections here to 25,405.
Dr Ronan Glynn, Deputy Chief Medical Officer, added: “COVID-19 is accelerating globally with 4 million cases recorded in the last month.
“Considering the international experience with the disease, we cannot afford complacency.
"Continue to be aware of the risks and follow the public health advice designed to protect individuals.”
