Dr Tony Holohan has said there is great concern about the Indian variant, describing it as a "big black cloud" hanging over Ireland.
Some 72 cases of the variant have been recorded in Ireland so far - a rise of 13 from a midweek tally of 59.
And speaking at NPHET's weekly press conference, Dr Holohan warned that though the outlook is positive, that could change very quickly.
The Chief Medical Officer said: "The situation is stable and the public are staying with us and our advice. The vaccination programme is rising on a daily basis. The skies are blue - but there is a big black cloud on the horizon that is the Indian variant.
"We are genuinely concerned about the variant and how transmissible it is. We'll have all that in mind when we meet next week about lifting restrictions in the near future."
Cillian de Gascun, Medical Virologist and Director of the National Virus Reference Laboratory, added: "We want to keep those clusters as small as possible.
"Really, it comes down to the same public health measures of the last 12-15 months. If you do these, the virus still needs to transmit from person to person and this variant is more transmissible. The measures can control the virus.
"You'll all remember how long we've monitored other variants and how successful we've managed that. But we're already at 72 cases of the Indian variant. It's very important that people take this seriously."
Dr Holohan also reissued a warning to those who are set to start their Leaving Certificate in the next couple of weeks.
"We reiterate our message to Leaving Cert students - take the opportunity to restrict your social contacts. Meet up outdoors, but make sure it is in a safe way. You don't want to pick up this infection and miss the exam," he said.
Dr Holohan was vaccinated with the Pfizer vaccine on Tuesday.
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Meanwhile, Taoiseach Micheál Martin has said the State is “tracking” the spread of the Indian variant “very carefully and closely.”
Mr Martin said variants “represent a continuing challenge” but the evidence so far “seems to be that the vaccines are giving protection and immunity against most variants so in terms of the Indian variant, we’ve got to again monitor that and see what's happening in the UK.”
He said: “We’ll be listening and engaging with our own public health advice in relation to all of that.”
And said there the vaccines are already providing “strong protection” and are reducing severe illness and death.
Mr Martin said NPHET will meet on Thursday and he will listen to NPHET’s advice on the variant.
There will be a Cabinet Covid-19 sub-committee on Thursday followed by a Cabinet meeting on Friday before the Taoiseach makes another announcement.
He said he will make an announcement around travel, sport and entertainment.
