𝐁𝐨𝐭𝐭𝐨𝐦 𝐥𝐢𝐧𝐞 𝐨𝐧 𝐭𝐡𝐢𝐬 𝐢𝐬 𝐭𝐡𝐚𝐭 𝐭𝐡𝐞𝐫𝐞 𝐚𝐫𝐞 𝐧𝐨 𝐩𝐫𝐢𝐯𝐚𝐜𝐲 𝐜𝐨𝐧𝐜𝐞𝐫𝐧𝐬, 𝐧𝐨 𝐝𝐚𝐭𝐚 𝐜𝐨𝐧𝐜𝐞𝐫𝐧𝐬 𝐚𝐧𝐝 𝐚𝐛𝐬𝐨𝐥𝐮𝐭𝐞𝐥𝐲 𝐧𝐨 𝐫𝐞𝐚𝐬𝐨𝐧 𝐰𝐡𝐲 𝐲𝐨𝐮 𝐬𝐡𝐨𝐮𝐥𝐝𝐧’𝐭 𝐝𝐨𝐰𝐧𝐥𝐨𝐚𝐝 𝐚𝐧𝐝 𝐢𝐧𝐬𝐭𝐚𝐥𝐥 𝐭𝐡𝐞𝐬𝐞 𝐚𝐩𝐩𝐬. 𝐈𝐟 𝐲𝐨𝐮 𝐰𝐚𝐧𝐭 𝐭𝐨 𝐥𝐞𝐚𝐫𝐧 𝐦𝐨𝐫𝐞 𝐨𝐧 𝐡𝐨𝐰 𝐭𝐡𝐞𝐲 𝐰𝐨𝐫𝐤, 𝐜𝐨𝐧𝐭𝐢𝐧𝐮𝐞 𝐫𝐞𝐚𝐝𝐢𝐧𝐠.

Importantly, these are not ‘contact tracing’ apps. Exposure notification apps simply notify you if you’ve been near someone who later tested positive for COVID-19. Contact tracing apps, however, let people log their location and share it with public health authorities. According to the rules Apple and Google have laid out, any exposure notification app that uses their technology cannot track locations.

𝐇𝐨𝐰 𝐝𝐨 𝐭𝐡𝐞𝐲 𝐰𝐨𝐫𝐤?

The app essentially sends out your random code (which changes every 5 minutes) to nearby phones and also listens for other phones transmitting their codes. It then stores that information. This is done using Bluetooth Low Energy (BLE) and occurs in the background after the app is installed. Teams have worked very hard to compress the data requirements, so it does not use your data or bandwidth and does not interfere with the normal activities on your phone.

𝐖𝐡𝐚𝐭 𝐡𝐚𝐩𝐩𝐞𝐧𝐬 𝐧𝐞𝐱𝐭?

If someone tests positive for Covid-19, they would then receive a key code that they can input into the app. 𝑰𝒏 𝑶𝒏𝒕𝒂𝒓𝒊𝒐, 𝒚𝒐𝒖 𝒄𝒂𝒏 𝒈𝒆𝒕 𝒕𝒉𝒊𝒔 𝒌𝒆𝒚 𝒘𝒉𝒆𝒏 𝒚𝒐𝒖 𝒄𝒉𝒆𝒄𝒌 𝒚𝒐𝒖𝒓 𝒕𝒆𝒔𝒕 𝒓𝒆𝒔𝒖𝒍𝒕𝒔 𝒐𝒏𝒍𝒊𝒏𝒆.

Once you input this key into the app and confirm that you have received a positive diagnosis, your app will send all the codes it has been broadcasting to a centralized database.

All phones regularly check with this centralized database. When someone tests positive, the centralized database sends out all their random codes and if there is a code that matches, then your app alerts you that you may be exposed and it gives you recommendations on what to do next.

Essentially the app notifies the phones that have passed within close range in the 14 preceding days. An exposure is counted based on how strong the Bluetooth signals are. If you are closer than 2m/6ft for longer than 15 min, it was recorded as a potential exposure in the app.

𝐖𝐡𝐚𝐭 𝐚𝐛𝐨𝐮𝐭 𝐩𝐫𝐢𝐯𝐚𝐜𝐲 𝐜𝐨𝐧𝐜𝐞𝐫𝐧𝐬?

As mentioned above, the app uses Bluetooth Low Energy (BLE) to do this exposure notification. It doesn’t use GPS, so no contact or location or any other private information is stored. In addition, even when the Bluetooth signal is sent, anonymous random codes are transmitted – so nothing that contains any personal identifiers are used.

𝗪𝗵𝗮𝘁 𝗮𝗿𝗲 𝘀𝗼𝗺𝗲 𝗼𝗳 𝘁𝗵𝗲 𝗰𝗮𝘃𝗲𝗮𝘁𝘀?

The flip side of using BLE unfortunately is that it is a new technology that was only released a few years ago. Due to this, older phones using iOS older than 13.5 cannot support it.

The other caveat is that there could be some discrepancies with respect to crowded locations – say for instance two apartments that are close enough to allow signals to be transmitted and received. However, the likelihood of this is low given that the signals only register an exposure of distance is within 2m/6ft and for greater than 15 minutes.

𝐅𝐈𝐍𝐀𝐋 𝐓𝐇𝐎𝐔𝐆𝐇𝐓𝐒:

𝐓𝐡𝐞𝐬𝐞 𝐚𝐩𝐩𝐬 𝐚𝐫𝐞 𝐚𝐧 𝐢𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐬𝐭𝐞𝐩 𝐢𝐧 𝐭𝐡𝐞 𝐭𝐞𝐬𝐭𝐢𝐧𝐠, 𝐭𝐫𝐚𝐜𝐢𝐧𝐠, 𝐢𝐬𝐨𝐥𝐚𝐭𝐢𝐧𝐠 𝐢𝐧𝐢𝐭𝐢𝐚𝐭𝐢𝐯𝐞. 𝐓𝐡𝐞 𝐨𝐧𝐥𝐲 𝐰𝐚𝐲 𝐰𝐞 𝐜𝐚𝐧 𝐛𝐞𝐚𝐭 𝐭𝐡𝐢𝐬 𝐯𝐢𝐫𝐮𝐬 𝐢𝐬 𝐭𝐡𝐫𝐨𝐮𝐠𝐡 𝐬𝐜𝐢𝐞𝐧𝐜𝐞, 𝐬𝐨 𝐩𝐥𝐞𝐚𝐬𝐞, 𝐈 𝐮𝐫𝐠𝐞 𝐞𝐯𝐞𝐫𝐲𝐨𝐧𝐞 𝐭𝐨 𝐝𝐨𝐰𝐧𝐥𝐨𝐚𝐝 𝐭𝐡𝐞𝐦 𝐚𝐬 𝐬𝐨𝐨𝐧 𝐚𝐬 𝐭𝐡𝐞𝐲 𝐚𝐫𝐞 𝐦𝐚𝐝𝐞 𝐚𝐯𝐚𝐢𝐥𝐚𝐛𝐥𝐞 𝐢𝐧 𝐲𝐨𝐮𝐫 𝐚𝐫𝐞𝐚.