By Adam Vaughan
How useful are apps for containing coronavirus outbreaks?
Steve Taylor / SOPA Images/Sipa USA
As countries search for ways to exit lockdown and avoid or manage a second wave of covid-19 cases, many have turned to the promise held by contact tracing apps. In a rare display of collaboration, Apple and Google recently partnered to help the technology work effectively.
Such apps look attractive to countries looking to lift restrictions, but there is growing evidence that it will be difficult to make them work. A simulation of a city of 1 million people by researchers at the University of Oxford, published yesterday, found 80 per cent of smartphone users in the UK would need to install a contact tracing app in order for it to be effective in suppressing an epidemic – that’s 56 per cent of the national population. The UK’s chief scientific adviser, Patrick Vallance, has indicated he believes such apps might have a role to play in contact tracing but that it would be a tall order to get 80 per cent of smartphone users in the UK to use them.
That is a tough target for the UKs NHSX, the National Health Service digital transformation unit, which is developing such an app. Surveys of 6000 potential app users in five countries suggest the level of take-up is unlikely to be this high. Results suggest that nearly 74 per cent of UK smartphone users would be willing to install a contact-tracing app, but in reality this could be a lot lower. In Singapore, only an estimated 17 per cent of the population has installed a contact tracing app launched last month. But even if app uptake is low, the University of Oxford team estimate that such technology could still cut cases and deaths.
The principle behind contact-tracing apps is fairly simple. Once installed, they use Bluetooth low-energy (LE) technology to record when a phone has come into close proximity with anyone else using the app. If either person later reports coronavirus symptoms, the other party is notified, so they could self-isolate or seek health advice. An alert could also be sent if a medical authority certifies the other person tested positive for the virus this would be one way to avoid users trolling the system by falsely claiming symptoms. In theory, the apps work anonymously and only store data temporarily, without collecting location.
But even if it was somehow feasible to get such high installation rates with voluntary take-up, there is the big question of whether using Bluetooth to establish a contact works well, said Katina Michael at Arizona State University and Roba Abbas at the University of Wollongong in a joint email to New Scientist. How reliable is the system to gather proximity information? The range of Bluetooth is much larger than 1.5 meters for social distancing, says Michael.
Ross Anderson at the University of Cambridge says the range of Bluetooth can vary greatly depending on how people hold their phones, and whether they are indoors or outdoors. He also points out the signals pass through walls, so people behind screens and in different rooms could be unnecessarily flagged as having had contact. The result could be a flood of false positives. Even the Oxford team, which is advising NHSX on its app, say the accuracy with which Bluetooth can be a useful proxy for virus transmission risk is currently uncertain.
A further potential issue is the quality of the data. Abbas and Michael say they understand that many apps being considered would only record contacts at five minute cycles, which might mean infectious contacts are missed.
There are a host of other questions. Key are trust between citizens and governments, how privacy is preserved, keeping the apps voluntary, and how to also protect people who might not have a smartphone or the ability to install an app – a group that is likely to include many vulnerable older people. The American Civil Liberties Union yesterday laid out a list of principles, including the need for an exit strategy for such apps, to avoid such systems being maintained for surveillance creep after an epidemic has passed.
Nevertheless, many countries are on the verge of deploying apps. Germany is expected to release one this month, and Australia is working on one too. One of the most high profile existing apps has been Singapores TraceTogether app, built by the city states government. But even its creators admit that it is too early to tell how effective it is.
Anderson is damning about the prospects for apps. Using them to trace contacts was always a long shot, he says, adding that it would be better to recruit thousands of people to undertake the tracing manually. Vallance thinks apps should be part of a much broader contact tracing approach, while the UK health secretary Matt Hancock said today that such apps were a critical part of government efforts.
However effective the apps turn out to be, they cannot be a silver bullet for exiting social distancing measures, and must be part of a much broader effort of testing and contact tracing.
Contact tracing apps are likely to be utilised as a means for fighting the spread of covid-19. However, they cannot be used in isolation. The apps themselves will not contain the spread, says Michael.
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By Adam Vaughan