On Wednesday, president Cyril Ramaphosa urged South Africans to use government’s new coronavirus contact-tracing app, which was launched earlier this month.

“I want to make a call this evening to everyone who has a smartphone in South Africa to download the COVID Alert mobile app from the Apple App Store or Google Play Store,” Ramaphosa said during his address to the nation. The app has been zero-rated by mobile networks, so you can download it without any data costs.”

Using Bluetooth technology, the app will alert any user if they have been in close contact with any other user who has tested positive for coronavirus in the past 14 days.

“Contact tracing is an important preventative measure to protect yourself and your close family and friends,” Ramaphosa said, as he announced details about South Africa’s progress to Level 1 on midnight, Sunday.

This will include the opening up of borders to foreign tourists from countries that don’t have high infection rates. These travellers will be asked to install the COVID Alert South Africa mobile app on arrival, Ramaphosa said.

The COVID Alert SA app is available for Android devices on the Google Play store and on the Apple App Store for iPhones, with the South African National Department of Health as publisher.

The small app, 2.1MB on Android phones and 5MB on iOS, promises to anonymously keep track of your contact with everyone else using it over a two-week period, the upper end of the incubation period for Sars-CoV-2. If a user discloses they have tested positive for the coronavirus, everyone in that contact list is notified.

The app uses the exposure notification framework created by Google and Apple for use during the pandemic.

“By downloading and using the COVID Alert SA app, you become a part of a powerful digital network of app users who choose to work together for the benefit of everyone in the app community while all enjoying complete privacy and anonymity,” the department of health promises.

“App users understand their exposure to Covid-19 and help others to do the same. We can all work together to curb the spread of Covid-19 and, ultimately, to save lives.”

The app is free, and uses only a small amount of data every day to check in with a central server. But it requires the power-hungry Bluetooth radio to be turned on, which makes for some battery drain.

COVID Alert SA does not record your name or location. Instead, every device is assigned a unique code. Using Bluetooth, it shares that code with other phones running the app when the come into range, and records the signal strength (a rough proxy for how close another person is) and date for any such contact.

The range of Bluetooth transmission can vary wildly depending on a range of factors, but is around 10 metres as a rule of thumb.

Anyone who tests positive for the coronavirus must type in a PIN number the department of health sends by SMS as part of the notification system for Covid-19 tests.

That triggers alerts other people who were in close proximity, without disclosing the identity of the infected person or any other details.

In such a case “[a]pp users are guided as to what to do next to optimise their wellbeing and prevent the spread of the Covid-19 virus to others,” says the department of health.

The usefulness of the app will depend on how many people install it, whether they keep their Bluetooth radios turned on, and how quickly they report positive test results.

Download South Africa’s official Covid-19 tracing app on the Google Play Store for Android phones, or on the Apple App store for iPhones.

Source: Business Insider, compiled by Phillip de Wet