Essential retail outlets will be the only allowed to remain open while public gatherings and house visits would be banned.
There's also to be a renewed focus on enforcement of the regulations in a bid to bring down the spread of the virus.
The National Public Health Emergency Team (NPHET) has made the stark recommendation as the country struggles to get to grips with rising infections, with nearly 1,000 cases confirmed over the weekend.
"For those aged 70-plus and those who are medically vulnerable to Covid-19, it is strongly recommended that you should limit the number of people you meet to a very small core group of family members, carers or friends, for short periods of time, while remaining physically distant", he said.
Under the Living with COVID-19 framework published by the Government, Level 3 allows visitors a maximum of six visitors from one other household to your own home. But when Level 5 was recommended, there was a stunned reaction from Government with one source saying: "This has surprised Government, given its societal and economic indications".
The advice, sent to Government in a letter on Sunday night, would need to be approved by Cabinet.
It is expected that the three party leaders in Government will seek a meeting with the CMO on Monday to discuss the matter.
There's no indication of how many new cases have been confirmed in Carlow or Kilkenny on Monday, if any.
In the past 24 hours, 365 more people tested positive for coronavirus while no further deaths were confirmed.
No new deaths were recorded, with the national toll standing at 1,810 fatalities.
"In contrast, the immediate application of level five is meant to limit the impact of public health of Covid-19".
Dr Gerry Waldron described the rise in the infection rate in the region as worrying.
"There is no doubt whatsoever about this, so we must respond and the challenge is to be as effective and proportionate as possible", Martin said in a televised address, announcing the move to Level 3 restrictions.
It is also not yet known whether a potential Level 5 increase would mirror the restrictions now listed in the government's Living With Covid-19 Plan.
"This is a real concern".
Instead every county will be placed on level three.
Schools and creches would remain open but all sporting events, elite or otherwise, would be required to cease.
He added: 'The worldwide evidence is that it can be done safely and I think our schools have done a good job in terms of making it safe for our students'.
Dr Tony Holohan, Chief Medical Officer, Department of Health, said; "We have seen in recent days a significant and concerning deterioration in the epidemiological situation nationally".