Language: English
Logo CoronaMelder app

How does the app work?

The app sends you an notification if for a certain amount of time, you have been near someone who has tested positive for coronavirus. The notification can help you avoid passing the virus on to other people without knowing it.

  • The app uses Bluetooth to detect other people who are near to you, as long as they have the app too.
  • The closer you are to the other person, the stronger the Bluetooth signal is.
  • The app works without knowing your location, name, e-mail address, phone number or other contact details. The app does not know who you are, who the other person is, or your location.
  • If you have been near another app user who later tests positive for coronavirus, the app will notification you of this.
  • If you test positive for coronavirus yourself, you can also choose to add this information to the app. This is voluntary. The app will then notification all the people you have been near to. This notification only tells them the day on which they were near somebody who has tested positive. It does not tell them who that person was, or where they were at the time.
My coronavirus test is positive. What happens now?

If you have tested positive for coronavirus, you can choose to add this information to the app, with the help of the GGD. If a GGD employee calls you with the test results, they will also ask if you want to warn other people using the app. Recipients of such an notification will not be able to see who you are or where you were near each other. You can decide whether these notifications are sent: it is not compulsory and it is not automatic.

What information is in the notification?

The notification will say how many days ago you were near somebody who has later tested positive for coronavirus. The notification does not say who that person was, and it does not say where or exactly when you were near them.

  • You can arrange for a test immediately after you receive an notification, even if you have no symptoms. The notification message from CoronaMelder will include all the information you need about how and when to do this.
  • If you have serious symptoms, or if you are part of a high-risk group, you should call your doctor.
Download this video
Written out text of the video

CoronaMelder - How does the app work

CoronaMelder. The app that helps you to avoid unknowingly infecting other people. How does it work? After you downloading it, the app exchanges codes with other phones that are nearby. The app generates codes for every phone. These codes are random and change several times per hour. If you are near to someone else - for longer than 15 minutes - who also has the app, your phones will exchange codes using bluetooth. But not if someone cycles past you in the street… only if you are near to each other for more than 15 minutes. CoronaMelder collects these codes in the app. Codes older than 14 days are deleted automatically. So CoronaMelder has a list of random codes from other users who have been near to you in the past two weeks. But when and how do you receive a notification? Let’s imagine that a week after you went out, another app user – let’s call him Max – tests positive for coronavirus. Together with the GGD, the Regional Public Health authority in the Netherlands, Max can add his coronavirus status to the app. There is a special GGD key in the app. Max passes this key on to the GGD health worker. The GGD health worker enters the key. Now Max can activate the list of codes on his phone. The app users belonging to those codes – including you! – will then get a notification. What’s in the notification? And what should you do next? The notification tells you which day you came near to someone who has tested positive for coronavirus. It does not say who that person was, or where it happened. If you get a notification, it means there’s a chance that you also have coronavirus. The app will tell you what you can do next and whether you should get tested. In this way, new infections can be discovered faster, which helps you to avoid spreading coronavirus to others. Downloading the app is voluntary at all times. We can only get coronavirus under control - together. More information? Visit