Dr Tony Holohan issued advice to families on how to have a safe Halloween.
The warning came as a further 2,966 confirmed cases of Covid-19 were reported by the Department of Health.
There are currently 470 people in hospital with the disease, with 92 of those in intensive care.
"Today we are reporting a high number of cases across the entire population, with the highest incidence amongst five to 12-year-olds," Dr Holohan said.
"While the Covid-19 vaccines give high protection against severe illness, hospitalisation and death, the way to break transmission is by following all aspects of the public health advice.
"This weekend, you can enjoy your favourite Halloween activities safely by taking some simple precautions.
"If you are having visitors over, provide hand sanitiser, open windows and try to ensure people can spread out and keep their distance from one another - avoid crowded parties.
"For trick-or-treaters, give out treats outdoors if possible. Wash or sanitise hands frequently, and before eating or handling treats.
"Neither children nor adults should go trick-or-treating or meet up with others if they have any symptoms of Covid-19, even if symptoms are minor - instead, please isolate and get a test."
The warning comes a day after the Taoiseach said Ireland could approve the rollout of Covid-19 vaccines to children aged between five and 12 in the next month.
The US Food and Drug Administration (FDA) recently approved the use of jabs for children in that age cohort, and the European Medicines Agency (EMA) is set to consider the same measure.
Micheal Martin said Ireland's National Immunisation Advisory Committee (Niac) will also consider the move, but it is "some weeks away".
He said: "You saw also the FDA, for example, approving the use of vaccines for children between five and 12.
"My understanding is the EMA will now give that consideration. When the EMA have given that consideration, Niac and our authorities will give that consideration."