Current Government advice allows people from four households to gather indoors.
However, Dr Holohan has now urged people to go further than this in the face of the threat posed by the Omicron variant and record case numbers being reported in recent days.
"We know that this variant is more transmissible than even the highly transmissible Delta variant. As such, please do not socialise or meet indoors with people from other households,” he said.
Dr Holohan also issued a stark warning to shoppers to avoid the annual post-Christmas sales and to shop online instead.
His comments came as another 10,404 cases of the Covid-19 were reported yesterday.
This followed a record number of 13,765 cases being reported on Christmas Day – the highest daily total since the start of the pandemic.
As of 8am yesterday there were 426 patients with Covid-19 in hospital with 50 new hospital admissions recorded over the previous 24 hours.
There were 91 people with the virus in intensive care units, the lowest number in ICU since November 9.
Covid-19 patients account for a third of all ICU beds currently occupied by critically ill patients.
The Mater Hospital in Dublin had the highest number of Covid-19 patients in ICU with 13 at 8pm on Christmas Day, followed by University Hospital Limerick with 11, St James’s in Dublin with 10 and Tallaght with nine.
The Department of Health now estimates that 83pc of all Covid-19 cases in Ireland are attributable to the highly transmissible Omicron variant.
Testing centres across the country remain extremely busy, with no pre-booked appointments available in many counties.
“It is important that all of us continue to reduce our contacts and avoid crowded places, to the greatest extent possible, as we see the Omicron variant become the dominant variant of Covid-19 in Ireland,” Dr Holohan added yesterday. “We know that this variant is more transmissible than even the highly transmissible Delta variant.
“As such, please do not socialise or meet indoors with people from other households.
“Avoid crowded places, including retail environments,” he urged.
“Choose to shop online where possible, queue outside and leave any retail environment that does not feel safe and is not adhering to the public health guidance – implementing social distancing measures and queuing system, limiting numbers in-store and staff wearing masks correctly.
“If you are yet to receive a booster dose of Covid-19 vaccine, then you should take every measure you can to protect yourself until you are eligible to receive it,” he added.
Dr Holohan said all of the available evidence indicates that a booster vaccine will offer good protection against infection with the Omicron variant.
“Our test centres are very busy at the moment due to the high incidence of Covid-19 across the country. However, it is important that you continue to self-isolate until you receive the result of your PCR test and further information from the HSE,” he said.
While testing centres operated at reduced capacity on Christmas Day and yesterday, vaccination centres remained closed.
However, all testing facilities and vaccination centres will reopen at full capacity today.
It comes as Ireland is on the brink of a milestone in the Covid-19 vaccine booster programme, with the number of doses administered due to reach two million.
However, Dr Holohan’s comments on avoiding crowded shops have caused some alarm among business owners who fear the advice is reminiscent of last year when the country went into lockdown.
Duncan Graham, managing director of Retail Excellence Ireland, said: “It feels a lot like 2020, and the last two weeks have felt like we are going back down that route.
“Certainly, the last thing we want to see is some sort of lockdown introduced like last year.
“We take our responsibility very seriously, and shops – by and large – are relatively safe environments.
“But it is going to be a more muted sale period than we would have seen before.
“I think over the past two weeks with the rising case numbers, customers have been taking a similar approach to shopping as they did last year so footfall is down, but they are still spending money and shopping online.
“Shopping centres will be quieter than they usually would be pre-pandemic