COVID-19 COVID-19 Analytics

How Effective Are Contact Tracing Apps? (Chloe Hadavas,

This article is part of Privacy in the Pandemic, a Future Tense series.

At the heart of recent debates on automated contact tracing in the U.S. and Europe has been the issue of privacy. The underlying assumption of these discussions is that contact tracing apps can serve as a kind of panacea—a way for societies to reopen with minor inconvenience—if only we can strike the right balance on privacy.

But we still don’t really know how effective contact tracing apps actually are—particularly in societies that don’t already have a vast surveillance infrastructure. The case of Iceland in particular, as the MIT Technology Review reported Monday, suggests we shouldn’t put too much hope on a digital solution:­ Although Iceland’s app has the highest penetration rate of all contact trackers in the world, it doesn’t appear to have helped much in addressing COVID-19.

Iceland launched a government-backed tracing app, Rakning C-19, in early April, a little more than a month after the country confirmed its first case of COVID-19. Before the app was developed, the government had already formed a team of contact tracers to interview COVID-19 patients and track down the individuals they’d recently encountered. The app, which is voluntary and relies on permission to release data, analyzes users’ GPS data to map where they’ve been in order to assist Iceland’s Contact Tracing Team. Location data is saved locally on users’ phones, and if the Contact Tracing Team needs your assistance, it has to send a request for the information. If users agree, their data is stored for 14 days in the Tracing Team’s database.


Promote health. Save lives. Serve the vulnerable. Visit

On paper, Rakning appears to be a great success. The app launched relatively early, and according to the Technology Review’s COVID Tracing Tracker project, it has the highest download rate of any contract tracer in the world, with 38 percent of the country’s population of 364,000 using it. (People have likely been more incentivized to download it, as well, since the app is unusually clear about how it stores data.) Iceland, meanwhile, has flattened the curve while avoiding large-scale lockdowns.

However, Gestur Pálmason, a detective inspector with the Icelandic Police Service who is overseeing contact tracing efforts, says that the impact has been small, especially compared with methods of manual contact tracing, such as phone calls. “The technology is more or less … I wouldn’t say useless,” Pálmason told the Technology Review. “But it’s the integration of the two that gives you results. I would say [Rakning] has proven useful in a few cases, but it wasn’t a game changer for us.” He explained that although Rakning has at times been useful, the desire to find easy technological solutions has led people to overstate the utility of such apps.

Iceland’s success in managing COVID-19 might instead be attributed to other factors, including the country’s early testing of high-risk individuals before it even confirmed its first case, wide-scale testing in the months since, that robust manual contact tracing system, and geographic isolation. This does not bode particularly well for countries—especially ones without those advantages—that have staked some of their reopening policies on automated contact tracing in the coming weeks and months. The British government, for instance, is counting on its app, which is currently being trialed on the Isle of Wight, to help ease restrictions.

Jason Bay, the product lead of TraceTogether, Singapore’s (voluntary) contact tracing app, has also warned against seeing automated contact tracing as a cure-all. In an April blog post, he wrote, “If you ask me whether any Bluetooth contact tracing system deployed or under development, anywhere in the world, is ready to replace manual contact tracing, I will say without qualification that the answer is, No.” There is simply too much critical information (like whether someone was in a place with adequate ventilation or even whether they were singing with a group) that an automated system can’t access, Bay argued. He emphasized that tracing should remain a human-fronted process, writing, “You cannot ‘big data’ your way out of a ‘no data’ situation. Period.”

China’s automated tracing system might be a more successful model, but as the Technology Review’s COVID Tracing Tracker notes, participation is involuntary, and there’s considerable lack of transparency—it’s still unclear how China’s technology works—which isn’t something Western countries could emulate. It’s also worth noting that China’s technology (and to a lesser extent, that of other East and Southeast Asian countries) supplements an extensive preexisting surveillance network.

Ultimately, the situation Pálmason described in Iceland aligns in part with an article the Brookings Institution’s TechStream published in April, which cautioned against the “fragile digital solution” of automated tracing creating a false sense of security. That article’s authors argued that contact tracing technology often doesn’t account for barriers as basic as walls, or personal protections such as masks, and thus would flag individuals unlikely to have been infected (or transmit the disease to others). The authors also predicted that the technology would eventually lead users to disregard warnings, after being flagged multiple times (like when your office fire alarm goes off constantly), and that it might negatively impact marginalized communities where people live in closer proximity to one another.

That’s why the authors of the TechStream article “urge developers of contact-tracing apps, as well the companies enabling their development, to be candid about the limitations and implications of the technology.” Your smartphone can help keep you safe—but it can’t do it alone.

Leave a Reply