People need to start reducing their casual socialising now if the country is to avoid falling back into lockdown as the daily number of new Covid-19 cases jumped to 34 yesterday.
Leading infectious disease consultant Professor Sam McConkey said people should be encouraged to interact only with small networks and create "social bubbles" with just one or two other families.
"Open up your social circle but not to hundreds of people, just another family or two," he said.
The national reopening is at risk as experts say there is an increasing likelihood that we are going backwards in the battle against Covid-19.
If the daily toll surges to over 100, the country could be back in semi-lockdown.
Fears of such a scenario grew yesterday after the number of new cases of the virus spiralled to 34, the highest it has been for weeks.
Earlier, Dr Cillian De Gascun, chairman of the expert group overseeing the virus, said if the daily number of new cases rose to 100 there is a risk the country would be plunged back into phase two of the exit from lockdown within weeks.
It would mean that people would not be able to travel more than 20km from their home.
Pubs and restaurants serving food, as well as some non-essential shops, would have to close.
A further three deaths from the virus were announced yesterday, bringing the toll to 1,752 so far.
"Covid-19 is extremely infectious. It wants to spread, but it needs people to come into contact with each other to do so," acting chief medical officer Ronan Glynn said.
"Physical distancing, hand hygiene and respiratory etiquette, wearing a face covering where appropriate and avoiding large crowds - are all actions each of us can take to cut the chains of transmission and stop this virus in its tracks.
"It now depends on the actions we take as individuals, as to whether this virus gets an opportunity to spread through our communities.
"Continue to follow the public health advice, know the risks, know the symptoms and stay safe."
The sustained rise in cases in the past two weeks marks a significant jump in levels of infection.
Most of the new cases of the virus caught in this country have been in people's private homes and through house parties, where large groups gather with no physical distancing.
Around one in five of the new cases are travel-related, where a person has come back with the virus or in cases where they pass it on to others to form a cluster when they return home.
However, just four cases in recent weeks relate to people who travelled here from the United States.
"Singing is one of the easiest ways to spread the virus because of the spray of droplets," Dr De Gascun said.
"If a young person arrived at a party and saw there was unsafe behaviour, they should turn around and go home and instead organise to meet their friends for a coffee.
"The public can have an impact on what happens in two to three weeks from now. We have controlled this already."
The next lockdown could involve measures imposed at regional level, although this may be difficult given the small size of the country.
There are also growing fears about the impact on hospitals if the spread of Covid-19 and seasonal flu combine strike the most vulnerable.
HSE officials told the Oireachtas Special Committee on Covid-19 Response that it has ordered 1.4 million doses of the flu vaccine for vulnerable groups. The vaccine is also to be extended to children aged two to 12.