People are having house parties "with abandon" and those invited to such gatherings must stay away, chief medical officer Dr Tony Holohan warned yesterday.
The parties are part of "unseen" breaches of public health advice causing concern and are being held as "though we are not in the midst of a pandemic".
It is still too early to have these kind of gatherings and they are against the current public health guidelines to halt the spread of Covid-19, he added.
Earlier this week, in response to questions on "intimacy" advice in the Netherlands, he agreed it was wise to stick to one partner to reduce the spread of the coronavirus.
He said yesterday it might seem to people that public health officials were policing "pleasurable" aspects of life and advising them in areas like house parties or intimacy.
However, although there was concern about people congregating on beaches or on train platforms, the real worry was "unseen" activities such as house parties, he said.
He insisted it was a matter of personal responsibility and people could choose not to organise or attend these kind of gatherings.
Avoid crowds, walk away and do not accept invitations to house parties, he urged.
He was speaking after the National Public Health Emergency Team met yesterday and recommended that the Government goes ahead with the second phase of easing lockdown next week.
Professor Philip Nolan, of Maynooth University, who is heading the team tracking the virus, said there was a very slight increase in the R number, the measure used to gauge how many people, on average, will be infected for every one person who has the disease.
He said it was difficult to measure with precision when cases drop to a low level, and it is between 0.4 and 0.7 compared to 0.6 last week.
However, he described this increase as "marginal" and was encouraged it is still significantly below one.
He said that the "easing of restrictions in phase one of the roadmap has not negatively impacted the R number, in no small part thanks to the collective behaviours of our population in preventing resurgence of the disease".
As long as the R value stays below one, the number of daily cases will continue to fall.
He said all the main markers of disease were showing a decline.
The number of new cases each day are at "unprecedented low levels" and there is a slow decline in all settings.
There are an average of 48 new cases confirmed daily, compared to around 60 last week.
Last week there were 178 patients in hospital and that total is now down to 144.
"We are looking at fewer than 10 admissions a day to hospital. The number in intensive care is down to 37 compared to 50 last week, with admissions down to around one a day," he said.
The number of deaths has also fallen to one a day.
Asked about the advertisements now being run by airlines promoting flights to Spain and Portugal next month, Dr Holohan said the advice to people was not to book a holiday.
"Now is not the time," he said, while reiterating that people should not engage in any non-essential travel.
Asked whether the Republic would follow the advice in the North to make the wearing of face coverings mandatory on public transport, he said the guideline here would remain that it should be voluntary.
Meanwhile, a widely available indigestion medicine - which can be bought in pharmacies here for just €8 - may curb Covid-19 symptoms in mild to moderate disease, a new study suggests today.
Famotidine, sold as Pepcid AC, is a popular indigestion relief to reduce the amount of stomach acid produced.
Famotidine can be taken in doses of 20-160mg, up to four times a day, for the treatment of acid reflux and heartburn.
The benefits of the drug on Covid-19 patients who were able to recover at home were felt within 24 to 48 hours , according to the findings of a small case series in the journal Gut.