Hello Jean,
It is great to know you want to visit Ireland.
As of now, Ireland will broadly align itself to the EU approach to non-essential travel to the EU from third countries. This means that if you are already vaccinated and no emergency brakes have been applied to the UK, you will not need to isolate or present a test. However, if an emergency brake has been applied, you will need to self-isolate, provide a negative RT-PCR test and take a post arrival test. An emergency brake is an EU measure coordinated to react swiftly to the emergence of a variant of concern or variant of interest of the virus.
You can find more details about these new measures on the
government website.
I hope this is all clear and let me know if you have another question.
Have a great day,
David.