Immuni is a technological solution that centres on an iOS and Android smartphone app. It helps us to fight the COVID-19 pandemic by notifying users at risk of carrying the virus as early as possible—even when they are asymptomatic. These users can then isolate themselves to avoid infecting others, and seek medical advice.

Immuni’s design and development are based on five main principles: utility, accuracy, scalability, transparency, and privacy.

It features a contact tracing system based on Bluetooth Low Energy:

- When two users come sufficiently close to each other for long
  enough, their devices record each other’s _rolling proximity
  identifier_ in their local memory. These identifiers are generated
  from _temporary exposure keys_ and change multiple times each hour.
  These keys are **generated randomly** and change once per day.
- When a user tests positive for SARS-CoV-2, the virus causing
  COVID-19, they have the option to upload to a server their recent
  temporary exposure keys. This operation can only happen with the
  validation of a **healthcare operator.**
- The app periodically downloads the new temporary exposure keys and
  uses them to derive the infected users’ rolling proximity
  identifiers  for the recent past. It then matches them against
  those stored in the  device’s memory and **notifies the user** if
  a risky contact has occurred.
- The system uses **no geolocation data** whatsoever,  including GPS
  data. So, the app cannot tell where the contact with a  potentially
  contagious user took place, nor the identities of those  involved.

To implement its contact tracing functionality, Immuni leverages the Apple and Google Exposure Notification framework. This allows Immuni to be more resilient than otherwise would be possible.

Besides the temporary exposure keys, the Immuni app also sends to the server some analytics data. These include epidemiological and technical information, and are sent for the purpose of helping the National Healthcare Service (Servizio Sanitario Nazionale) to provide effective assistance to users, in compliance with art. 6.2.b and 6.3 of the Law Decree 28/2020.

Immuni is being developed while paying a lot of attention to user privacy and a number of measures have been taken to protect it. For example, the app collects no personal data that would disclose the user’s identity, such as the user’s name, age, address, email, or phone number.