Dr Tony Holohan has suggested cancelling Christmas plans after Ireland was hit by a surge in Covid-19 cases.
The latest figures from the Department of Health revealed that a total of 764 more people have tested positive for coronavirus in Ireland, while four more deaths have been confirmed.
It brings the number of infections here to 79,542 since the pandemic began.
A total of 284 of the new cases were in Dublin, with 70 in Limerick, 52 in Donegal, 44 in Cork, 37 in Wexford and the remaining 277 cases are spread across another 20 counties.
Speaking on today's figures, Dr Holohan suggested that anyone who has been socialising in recent days and weeks should consider cancelling their Christmas plans.
He said: “Every indicator of disease severity is moving in the wrong direction, more rapidly than we had anticipated. We have particularly strong concerns about the prospect of inter-generational mixing around the festive season. On 11th December the 7-day incidence rate for people aged 19-44 was 106 per 100,000 population, by yesterday this rate had more than doubled to 217 per 100,000.
"If these younger people come into contact with their loved ones over the age of 65, we could see a spike in infections in this more vulnerable group. This would lead to very a serious pattern of disease, hospitalisations, ICU admissions and unnecessary deaths.
“If you have been socialising in the past few weeks or over this weekend, consider your Christmas plans carefully. Is it responsible to meet with your family over 65 later this week, if you have not kept your contacts low? Should you cancel your plans?
"We have the very real prospect of COVID-19 vaccines on the horizon. Ensure that your loved ones stay alive to receive them, by keeping your distance from them if you have not restricted your movements to this point.
"As difficult as it may seem, staying away from older family this Christmas will protect them - and it would be an exceptional sacrifice made for the common good.”
