Thousands of people who have booked summer holidays abroad should cancel them amid fears Ireland could be seeing the first signs of a potential resurgence of Covid-19.
Chief Medical Officer Dr Tony Holohan issued the warning in the wake of a small but worrying rise in clusters of travel-related infections and an increase in cases of the virus in young people flouting rules.
The slight turnaround in the pattern of infection has stoked fears of a potential flare-up in the virus and comes as pubs, restaurants, hairdressers, hotels and a range of businesses welcomed back customers for the first time since March yesterday.
One of the clusters of the virus in recent days has been linked to a person who transported it back here from Iraq.
The fear is that as more people go abroad for summer getaways, they will pick up the infection and spread it when they arrive back.
"I know people have made bookings. It would make much more sense not to go ahead," Dr Holohan said.
People were putting themselves, companions and close contacts as well as the wider community at risk, he warned.
Dr Holohan reported 24 new cases of the virus yesterday, but no deaths.
The reversal in the previously downward trend in cases has been spotted in the last five days.
Dr Holohan admitted it was early days and the rise may not be sustained, but he was not yet drawing conclusions.
"We need to watch it very closely and see if it is something we need to do something about. It's the kind of thing we need to pick up early," he said.
A rising proportion of cases are being seen in young people and one person who tested positive had more than 20 contacts compared to an average of two to three seen in April at the height of the pandemic.
Dr Holohan had seen young people along the Grand Canal in Dublin wedged together near pubs they used to frequent.
The breaches were not confined to young people, he added, and older age groups were socialising, frustrated at the limitations of lockdown.
The last Government promised that a green list of countries would be available by early July, revealing countries with a low level of virus likely to welcome Irish holidaymakers without quarantine restrictions.
Dr Holohan again warned yesterday that destinations like France and Italy would not make it to the list and more information was needed from the European Centre for Disease Control, which is examining virus spread in EU regions in advance of any "air bridge" agreements.
Siobhan Killeen, the Dublin GAA footballer who contracted the virus in March and was among the speakers at yesterday's briefing on the virus at the Department of Health, said: "I, probably like many others, was naive in thinking that my age and health would protect me from a very infectious disease."
In a direct message to other young people, she added: "The after-effects of this disease are very serious, even for those who are fit and healthy. I was in very good health, but it was a very tough battle."
She said younger age groups would not want the guilt of knowing they had infected others.
A poll commissioned by the Department of Health showed 45pc now claim to wear face masks, up from 41pc last week.
There is scepticism whether these figures are accurate, with more than 50pc of women but just a third of men saying they cover up.
There is growing concern about a resurgence of Covid-19, with 64pc believing there will be a second wave.
Some 25pc of people want more restrictions and nearly a third feel lockdown exit is happening too quickly.
The doubts come despite the country enjoying its biggest taste of freedom yet in the ongoing relaxation of rules.