Trinity researchers have raised fresh doubts over the accuracy of contact tracing apps – already in use in Switzerland, Germany and Italy, and likely to be rolled out in Ireland at some point – warning of several problems with the technology.
In May, Prof Doug Leith and Dr Stephen Farrell made headlines when they published research that found that “the strength of the received Bluetooth signal can vary substantially depending on whether people walk side by side, or one behind the other”.
Now, the researchers have published two new studies, which flag issues with the “lack of transparency” of updates to the technology, as well as demonstrating low levels of accuracy when it comes to its use on commuter buses.
The findings shroud the effectiveness of the technology – in the works since March, but delayed due to doubts over its dependency and privacy concerns – in further doubt.
Leith and Farrell are currently working with the HSE and Department of Health to test the technologies that underpin a contact tracing app that the government hopes will help Ireland’s ongoing response to the spread of the virus.
They warned today that the “radio environment” of a commuter bus – something the researchers think is caused by the metal all around the bus – severely compromises the accuracy of the technology’s ability to detect people’s proximity.
On a bus, they found, signal strength between phones can actually be higher on phones that are far apart compared to phones that are closer together – something Leith said in a press statement makes “reliable proximity detection based on signal strength hard or perhaps even impossible”.
As well as testing it on buses, Leith and Farrell analysed how the technology – developed by Google and Apple – works on Android headsets.
They found that the way it measures Bluetooth low-energy signal strength – probably to save on battery power, they say – can make it “much more inaccurate at estimating proximity”.
And they warned of issues when it comes to updates to the technology that can be installed on phones without telling users, and with no opt-out option – including “updates that can significantly affect contact tracing performance and, in turn, public health”.
This, Leith said, “raises obvious concerns regarding oversight, and highlights the need for the governance of changes made by Google/Apple when it will eventually be deployed in Ireland”.
