An immunology professor has said it will be 'virtually impossible' to keep a new strain of the coronavirus out of this country if it reaches Northern Ireland.
The mutation - known as VUI-202012/01 - is said to be up to 70% more infectious than the original strain because it has a much bigger viral load.
Cases of the new strain have been spreading rapidly in the UK, and have led to a travel ban from several other countries - including Ireland.
However there are no travel restrictions in place between Britain and Northern Ireland - with concerns people can then take trains from Belfast to Dublin and other places.
Professor of Experimental Immunology at Trinity College Dublin (TCD) Kingston Mills told The Hard Shoulder people must isolate on arrival here.
"We know that there are changes in this variant compared with what had previously been circulating".
"If people don't isolate when they come back from travel, especially from the UK, I know we've got this temporary ban now in place - but obviously people will have come in already.
"And if they haven't got themselves isolated before they get themselves tested and shown to be negative, then they're at a risk of transmitting it to the rest of the country".
He said it is going to be "very hard" to keep it out of Northern Ireland.
"There are more flights going into then North from the UK mainland than there is from the UK to Ireland.
"So it is going to be virtually impossible to keep it out of Southern Ireland if it gets into the North".
"We've already seen all the border counties are probably the worst-hit areas right now because of proximity to Northern Ireland".
He added that testing is crucial for people who arrive into the country.
"Really what we want everyone to do - especially the people that have come from the UK that are already in the country - to really get themselves isolated from others... and get tested to show that you're negative.
"Then if you're negative five days after coming in, it's OK because there's a good chance you won't be infected".
While cases of the new strain have also been confirmed in Denmark, Italy, the Netherlands and Australia.
French Health Minister Olivier Veran said it is "entirely possible" the new variant is already circulating in France, but no cases have been officially identified yet.
First detected in London and south-east England earlier this month, it is now present in all parts of the UK apart from Northern Ireland.
According to data from the European Centre for Disease Prevention and Control (ECDC), the UK has one of the highest capacities in the world to test for the genomes found in the new COVID variant.
Additional reporting: IRN