A member of NPHET is expressing concern about plans to ease almost all restrictions on October 22nd.
It comes as COVID-19 cases have increased by 43% over the past week, with 2,066 reported on Wednesday.
The 14-day incidence rate has risen by 12% in the last seven days, and hospital numbers are at their highest since March.
NPHET is to meet on Monday to decide whether to give the go-ahead for measures to ease on Friday week.
Among measures set to be lifted are requirements for physical distancing, requirements for mask wearing outdoors and in indoor private settings, and limits on numbers at indoor and outdoor events.
Dr Mary Favier says the planned easing of restrictions may need to be 'tempered'.
"We would be no longer looking for things like vaccine certificates to go indoors, we would no longer be looking at any distance limitations indoors, and no longer wearing masks indoors.
"And you can imagine the pubs across bank holiday weekends in those circumstances.
"And very difficult scenarios in terms of hotbeds of infection.
"So there needs to be some concern about that; it's not to say 'Don't ease the restrictions' but caution about how, and perhaps temper how they're done."
And Dr Favier says the biggest concern is not around case numbers, but hospital numbers.
"The concern would be if we had further easing in restrictions in the next week or two or three is 'What would be the impact on that?'
"I think the impact isn't so much on the case numbers, it's on the impact into our hospital system - which is really feeling the strain
"And so that will be the concern: Can our hospital system manage over the next number of weeks and months if we ease restrictions?
"And that will be what will need to be balanced".
Meanwhile Taoiseach Micheál Martin has said a decision is expected in the coming days on the further rollout of booster vaccines.
He told his parliamentary party on Wednesday night they will be rolled out 'without delay' as soon as the National Immunisation Advisory (NIAC) makes a decision.
They are already recommended for all over-80s - and over-65s in nursing homes.
And he warned that the major easing of restrictions planned for next week cannot be guaranteed.
"Presentations were made to officials and I received a briefing on that this afternoon in respect of the growth of the seven-day incidence and in terms of the pattern of disease affecting all age groups now at this stage," he said.
"That is a matter of concern. That is what I am saying right now and therefore we have to feed that into whatever decisions we make early next week."
Reporting by: Eoghan Murphy