Sligo has recorded 13 new coronavirus cases in less than a week after previously having a great record with the disease.
Even with the new outbreak there have only been 138 cases in the western county, according to the latest figures.
Dr Tony Holohan mentioned new clusters in the Department of Health briefing on Monday and cited international travel as the reason behind them.
The current Sligo cluster is linked to a family who travelled back from the middle-east to their home in the county having previously headed away in February.
Despite being asymptomatic, the three members of the family were in contact with a small few people which led to a mini-outbreak in the area.
All their contacts have been traced and those involved are believed to be following guidelines and self-isolating.
Dublin and Kildare are the other two counties that have seen surges in numbers with 29 and 9 new cases in each respectively in the past four days.
Dr Tony Holohan has repeatedly warned that international travel poses a massive risk in terms of sparking another major outbreak.
He said previously: "We’d like people not to travel, yes.
“It makes much more sense to not go ahead with that booking and to risk travelling abroad, picking up this infection, risk for you, for any family member you be travelling with or indeed any close contacts you have.
"I think that would be not just in your individual interest but in our collective interest."
Speaking about the recent spike, he added: “We are starting to see a worrying trend, with the number of reported cases increasing, and some new clusters.
“As restrictions are lifted and people move about more, it’s important that we use the tools that have helped us suppress the virus to date.
“Hand washing, physical distancing, cough/sneeze hygiene and wearing face coverings are important personal behaviours that mean, as we go about our daily lives, that we are doing everything we can to avoid contracting the virus and spreading it to those we love.”
