The app has been live since midnight.
60% of people will need to download the new Covid Tracker app in order for it to be effective, according to the HSE.
The app identifies people who've been within two metres of a confirmed case for over 15 minutes and sends them a notification.
They'll then be advised whether to get tested, and to isolate and limit their interactions with other people.
Paul Reid, CEO of the HSE said it'll take time to build up the numbers using the app.
''There has been some analysis that would say you need up to 60% penetration.
''But when you start to look at the population that we have, I think to build the momentum is the most important thing first.
''And we're off to a great start''.
Since the app went live last night, around half a million people (at the time of writing) have registered so far.
If you wish to download the Covid tracker app, you can do so here.
