The Acting Chief Medical Officer Dr Ronan Glynn has singled out four counties over increased COVID-19 cases in the past week.
He has asked people in Cork, Galway, Monaghan and Roscommon to continue to follow public health advice, reduce social contacts and keep their distance from others.
He said people should assume that they or those with them are potentially infectious.
Dr Glynn said: "I am asking everyone, but particularly those living and working in Cork, Galway, Monaghan and Roscommon, to adhere to the public health advice.
"There is still time to get the virus back under control in these areas, break the chains of transmission and stop the spread of this highly infectious disease in these communities.
"We know the key actions to take to stay safe, by keeping a 2m distance, reducing your social contacts, wearing a face mask, covering coughs and sneezes and staying at home and contacting your GP if you start to feel unwell, you are doing everything you can to take care of yourself and those around you."
He also gave an example of how COVID-19 can spread if given the opportunity, with a graph showing how one case led to a cluster of 56 cases.
"Please keep it small, keep it safe & keep your distance", he said in a tweet.
"If you have symptoms please isolate immediately.
"If you are a close contact please restrict your movements - do not go to work, uni or meet with friends".
Lorna Fitzpatrick, president of the Union of Students in Ireland (USI), also made a plea on Monday.
She said: "This is a really difficult time for young people, but students have a vital role to play in keeping everyone in the community safe.
"My message to students today is to keep the public health guidelines in mind when you are making plans and decisions about where to go and who to see.
"Also, it is so important to take care of your mental health at this time.
"Make sure you are reaching out to friends and family on the phone, online and in small, safe ways in person.
"Remember that talking to others and asking for help when you need it is essential at the moment."
It comes as 390 further cases of coronavirus were reported here on Monday.
Of those 209 cases are in Dublin, 27 in Cork, 22 in Donegal and 21 in Galway.
There are also 14 in Kildare, 14 in Monaghan, and seven each in Roscommon, Tipperary, Waterford and Wexford.