Dr Tony Holohan has delivered a stark warning that 200,000 people could be infected in December as Covid-19 cases continue to skyrocket.
The CMO has urged the public to take action now to ensure their safety and the safety of loved ones.
He told RTE Radio 1 that over 200,000 people could be infected with the virus over the month of the December if things do not change drastically - and out of these 200,000, 4,000 could spend Christmas in hospital.
He said: "20 out of every 1,000 of those will end up in hospital.
"They will all be advised to restrict their movements, to self-isolate and their contacts will be advised to restrict their movements.
"That's a lot of people in hospital, potentially 4,000 or more. It's a lot of people being asked to self-isolate and restrict movements.
"None of those people are infected yet and at the time of year where none of us wants to be faced with going into hospital or having a loved one going into hospital.
"For people listening, this is not inevitable. If you're going to have an infection in December, that infection has not been picked up yet. There's still two weeks between now and the beginning of December.
"Each one of us can take simple measures."
The CMO said that these measures include isolating if you are a positive case and taking difficult personal decisions about discretionary socialising in the run up to Christmas.
Dr Holohan asked employers to do everything they can to make sure that people can work from home, if at all possible.
He stressed that many people are already cancelling their Christmas nights out because of the virus.
"We are advising people to stay at home and work from home if at all possible," he said.
"I know that this is the case, I know it from my own life that people are making these kinds of decisions as ways of reducing their own risk and ways of reducing the risk to their loved ones and their friends.
"We all understand the value of Christmas, particularly in this country. These are responsible decisions, decisions that nobody wants to be taking at this time of the year of course."
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