| One of the numerous problems with the very concept of Bluetooth-based contact tracing is: it doesn't work. Due to all the hardware and environmental factors, it really works as a large spreadsheet of all devices in Bluetooth range over the last 21 days (in the case of the Australian COVIDSafe app). All it can do to grasp at the environmental context is to record the phone model, and the RSSI over time. In a dynamic, real-world environment that will vary hugely, especially on public transport, as human bodies could be in the exact same close spot, but due to phone position and rotation the RSSI will vary wildly (as mentioned in the video), making two people close to each other actually look 20 metres or more away. The huge amount of contacts each have to be manually contacted and interviewed to determine whether they're epidemiologically relevant. That also relies on the recall of the infected and the false 'close contacts' who are at risk of having to isolate for up to 14 days regardless of test or symptoms (according to a reading of the Australian rules). This reality is extremely divorced from the Oxford University paper, which imagined a system that could accurately determine proximity of users and instantly notify them to isolate. This rapid notification and isolation was, in fact, the central proof of the impact of a digital contact tracing system. So we have a centralised system that: * only 'works' in a 'mandatory install' context * can't determine proximity in the real-world (too much variability) * would introduce huge numbers of false positives into a system that has to manually follow-up every one * normalises carrying a tracking device of all nearby people (which in future would be far more useful as a societal monitoring system than as an epidemiological tool) |