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The COVID Tracker app is part of our contact tracing operation.

It uses technology developed by Apple and Google called Exposure Notification System (ENS). ENS is free and is on most phones less than 5 years old. You need to update your phone's operating system to be sure that you have it.

ENS uses Bluetooth and randomly-created IDs to anonymously log:

  • any phone you are in close contact with that also has the app
  • the distance between your phone and another app users' phone
  • the length of time your phone is near another app users' phone

It does not track or use your location. The app does not know where you have been or who you are with.

Read about why you should use the app and how it can help us all stay safe.

The app also works with similar apps by other health services, including Northern Ireland, Germany, Italy, Denmark, Spain, Hungary and Latvia.

How the app works

Every 2 hours the app downloads a list of random IDs. These IDs are shared anonymously by app users who have tested positive for COVID-19 (coronavirus).

If you have been closer than 2 metres for more than 15 minutes with any of these people, you'll get an alert that you are a close contact.

The app does this work in the background. This means you can use your phone as normal.


Bluetooth on your phone needs to stay on for the app's contact tracing system to work. You'll be asked to give the app permission to use the Exposure Notification System (ENS) when you first use the app. This will also turn on Bluetooth.

The app uses Bluetooth low energy (LE) to estimate the distance and time spent between app users. It will be able to accurately tell if you have spent 15 minutes or longer near someone who tested positive for the virus.

Most of the time it will also give an accurate estimate of the distance between you and this other app user. But it's not perfect. No method of contact tracing is 100% perfect.

That’s why we use 2 methods of contact tracing - our contact tracing team and the COVID Tracker app.

Random IDs

The Exposure Notification System (ENS) allows phones to share random IDs using Bluetooth.

These IDs contain information about how close you were to another app user and how long you were close to them. They are codes made up of letters and numbers. You never see them. They cannot be used to identify users or their phones.

Using a random ID means all information is collected anonymously. No one will ever know your personal details unless you choose to share them. This includes the HSE.

Read more about privacy and how we use your data.

Mobile data use

The app uses about 1MB of data per day. This is about the same amount of data you would use for 6 minutes browsing the internet.

Battery life

Using the app shouldn’t make a difference to your phone's battery life. The app uses Bluetooth low energy. This is the same technology used by smartwatches or wireless earphones. It's designed to be energy efficient. 

Last updated: 26 November at 3pm

page last reviewed: 26/11/2020
next review due: 26/11/2023