Swim Ireland's proposed winter nationals, due to take place from 17-20 December at the National Aquatic Centre (NAC) in Dublin, will now be strictly for elite swimmers.
The Level 3 restrictions currently in place state that no matches or other sporting events should take place, apart from 'elite' sports.
Normally up to 600 swimmers would take part in a winter nationals event, but that is likely to be trimmed to around 40 elite athletes this time.
"Under the enhanced level three restrictions that came out on Friday of last week, it was clear that the only competitions that could take place in Ireland during that period was for the very top of each sport," said John Rudd, Swim Ireland's high performance director.
"It meant that the number of competitors that we'd hoped to be able to accommodate was significantly reduced and therefore, a four-day meet just wasn't necessary to cater for what now will be quite a limited number of athletes."
It's now likely that the meet will be reduced, depending on the level of entries and Swim Ireland will be writing to their elite swimmers with an offer of entry.
"Some people now may decide that it isn't something that that they want to do," said Rudd.
"And some will also consider whether they've had enough training going into this, particularly with the Northern Ireland athletes, who are currently in a period of two weeks without swimming pools.
"I'd hoped that we'd have somewhere in the region of 30 to 40 athletes able to compete but how many will take up the actual opportunity, we'll find out in the days to come."
Swim Ireland are running a unique event at the NAC, with a short course (25 metre) event in the mornings, followed by long course (50 metre) finals in the evening.
The only Irish elite swimmers to see any action since the first lockdown have been Shane Ryan and Darragh Greene, who took part in the recent International Swimming League in Budapest, while Mona McSharry is now training in the USA and will not be at the NAC for the winter nationals.
Tokyo and the Olympics are now also on the horizon and only Greene has swam an Olympic consideration time, for the men's 100-metre Breastroke
"Tokyo very much is on our minds and we're also three months into the Paris (2024) Olympic cycle.
"And, and it would be very short sighted of everybody in sport, not to keep that very much at the forefront of their mind as we go into 2021 and to remember that we're already less than four years away from the Paris Olympic Games."
Swim Ireland are targeting running their Olympic trials at the NAC next April.
"The April trials in Dublin will be for the individual events, while the European Championships approximately three weeks later in Budapest in May are the trials for the relay events and we'll be sending a strong contingent of relays to Hungary."
All this action will like depend on the roll-out of an effective vaccine for Covid-19 and Rudd says swimmers should be ready to be vaccinated, provided its proved to be safe and effective
"I know that there's a lot of people out there that would be that would be anti vaccine, and would be suspicious of where some of the vaccines are coming from.
"(But its going to be a) very difficult life for years to come without this vaccine.
"So I would be encouraging athletes to take this as soon as it's available to them, to give them that assurance and that confidence for their sport."
