Counties Cork, Louth, Waterford, Wicklow, Kildare and Galway have been put on alert as a spike in Covid cases has seen Donegal move to level 3 restrictions.
Taoiseach Micheál Martin has made a direct appeal to the public to limit their social contacts as much as possible, stating it is "only we as a people acting together, and holding firm in a spirit of solidarity that can slow its destructive spread".
It comes as 324 new cases of Covid-19 were confirmed, with 167 cases in Dublin, 42 in Donegal and 34 in Cork.
Acting Chief Medical Officer (CMO) Dr Ronan Glynn said gatherings and celebrations such as significant birthdays, communions, weddings and garden parties involving extended families and close friends have been a significant factor in outbreaks.
One in four cases in the past two weeks has been in those aged between 15 and 24 years and Dr Glynn pleaded with younger people to set an example for others.
"I'm asking people everywhere, but particularly in Donegal, in Dublin and more broadly in Louth, Kildare Wicklow Waterford, Cork and Galway to pay particular attention to the public health authorities.
"Prioritise who you need to see, limit the size of your social network," he said.
"I do not want to be back here next week or the week after," Dr Glynn told a press briefing after the Cabinet accepted NPHET advice to introduce further restrictions in Donegal.
"Keep your distance, wear face coverings and don't go to work, don't send your children to school, don't interact with others if you have any symptoms," he said.
This was echoed by Mr Martin who said "there is every chance we could have similar announcements in other areas."
The Govt has decided to move Donegal to Level 3 under the Plan for Living with Covid-19 from midnight tomorrow following public health advice from NPHET. This is in response to rising Covid 19 cases in the county.— Micheál Martin (@MichealMartinTD) September 24, 2020
For more visit: https://t.co/z1gcv7Lo8z pic.twitter.com/GOD90Tf8Hs
Donegal now has the highest incidence rate of the virus in the country, in the Lifford-Stranorlar local electoral area, 87 separate cases have been confirmed over the past two weeks alone, giving a 14-day incidence rate of 336.1.
This is over five times greater than the average incidence rate across the country, which now stands at 70.7.
Donegal will now move to Level Three from midnight (midnight Friday) meaning all matches and sporting events will be cancelled and people will be asked not to travel out of or into the county unless essential.
Like Dublin, visitors to private homes and gardens in Donegal should be limited to a maximum number of six from one other household and people have been asked to work from home.
Weddings will be allowed to go ahead with 50 guests this weekend, however, this will be reduced to just 25 people from Monday and guests will not be allowed to travel from outside the county to attend.
While wet pubs in Dublin did not reopen when restrictions were imposed last week, all pubs and restaurants in Donegal can continue to trade, however, this will be limited to serving a maximum of 15 people outdoors.
Dr Glynn said public health doctors are reporting the virus is spreading between families and extended families who are "dropping their guard" because they know each other.
He said: "This is becoming a common theme across the country that because people know each other because you meet up with your friends, your families, and assume that they cannot give it to you.
"The reality is that neither they know or you know whether you are they are infectious or they are infectious."
He said people must act as if those in their company are infectious and have the potential to transmit the virus.
The Taoiseach also spoke with Michelle O'Neill and Arlene Foster yesterday given the rising figures in Derry and its proximity to Donegal.