Contact Tracing: Halting the Coronavirus Pandemic with Your iPhone

When I first heard the term contact tracing mentioned in the context of a phone app, my immediate thought was, “Oh no.” With a sinking feeling, I flashed to my Google Maps location history that records exactly where I’ve been every single day and what could happen if the government demanded all that data not just from me, but from everyone. On the one hand, it would be really useful, perhaps even lifesaving, to get an alert on my iPhone if someone I’ve come into contact with recently is diagnosed with Covid-19. The coronavirus pandemic, after all, has killed nearly 500,000 people worldwide at this writing, according to the World Health Organization. On the other, nobody wants to arm the government with perfect knowledge of their movements and friendships. This seems a hard choice: surrender more privacy or accept the risk to your life. In order for contact tracing on the iPhone to be effective, epidemiologists say at least 60 percent of a population needs to participate. Unless our privacy concerns are adequately addressed, many will hesitate to opt in, despite the threat to public health. Amazingly, there is a technical solution that mostly resolves this dilemma. It turns out, Apple and Google have joined forces to create a voluntary system that addresses privacy concerns in quite an ingenious way.

Related: The Rise of Telehealth: After the Pandemic, There’s No Going Back

What Exactly Is Contact Tracing?

Contract tracing has traditionally amounted to trained sleuths asking the victim of an infectious disease who they’ve had contact with to figure out who they might have transmitted it to. The goal is for public health officials to make a list of people exposed to infection and alert those people for self-quarantine. If you can do that, then you can stop the spread of the disease without having to issue general lockdown orders.

This analog version of contract tracing, relying on human memory and detective work, is tough and time-consuming, but it’s also an incredibly important part of the complete pandemic-fighting toolkit. So, like everything else these days, we look to technology to help. It seems a small enough leap: our phones already keep track of our locations. Surely all that information could be harnessed for the public good?

Israel’s contact-tracing app works that way: by reviewing all the movements of an infected person and alerting those who may have crossed their path. But analyzing existing location data is a serious invasion of privacy. Most contact tracing apps have found a different way.

How Contact Tracing Works on Smartphones

The majority of contact-tracing apps use low-powered Bluetooth signals to identify when a smartphone is near another smartphone. The antennas can detect signal strength and use that to guess how far away the other phone is. This allows every device to collect its own contact history: which other devices has it been near, and for how long? Deciding what else it should collect and what to do with the data have become points of controversy. Should it capture the location of the contact, for example? What about the medical history of the two parties? Both of those would be helpful to public health workers, but only if the data is also compiled in a government database that they can access.

A centralized database of everyone’s recent contacts, potentially augmented with their locations at the time, could allow scientists to better track the disease. It could also be open to abuse and a tempting target for hackers; witness Qatar, where the government made use of its contact-tracing app mandatory for all citizens. The app gathered location data, and then researchers from Amnesty International found that it had a serious security vulnerability that may have exposed its data to hackers. Should a database like that get leaked, it could be used for all kinds of nefarious purposes. Imagine an internet stalker with access not just to your location and movement patterns, but a perfect list of everyone you’d met with, and you’ll see why this is nightmare material.

Concerns like these didn’t stop a long list of public health services, including those in South Korea, Singapore, Australia, Israel, and the state of Utah from developing their own apps, using a variety of implementations. But this piecemeal approach faces some hardware problems.

The Need for a Contact Tracing Standard

Apple limits the access that third-party apps can have to sending and receiving Bluetooth signals in the background. This is an important privacy issue. Apps with unfettered access to Bluetooth could do exactly what a contact-tracing app is meant to do, but without government oversight or the raison d’être of the Covid-19 pandemic. So Apple normally restricts apps’ Bluetooth access when doing background tasks. The result is that without special access, the app has to be open on your iPhone and the screen unlocked in order to register nearby phones. This drains battery fast and is impractical as it expects millions of users to keep an app open at all times. Because of that, governments had to turn to the companies that actually make mobile operating systems for help. As you might expect, different governments have asked for different things. Some would prefer that the contact data not stay on the phone, but instead be aggregated into a centralized database (like Qatar). Some would like the contact data to include location data. And of course, there are the countless details of implementation inherent to any engineering project that might turn out to have security or privacy ramifications.

The Apple-Google Partnership

Enter the Google and Apple partnership. The intent is to jointly roll out a standard for a contact-tracing system that’s strictly voluntary, and that presents a united front on privacy issues while giving governments the tools they need as quickly as possible. The combined bargaining power of Apple and Google, which together represents essentially 100 percent of the phone operating system market, gives their demands serious teeth. And, their demands are seriously skewed toward privacy. Instead of a centralized database of locations and movements, the solution they proposed is distributed and local. Apple and Google’s protocols only collect contact information, they don’t touch the Health app or your location data, and they keep the list of contacts encrypted, sanitized of all personal and identifying information, and stored locally, with every individual device storing only its own history. If someone in the program gets a positive diagnosis for Covid-19, they can opt in to share their phone’s encrypted identifier so that the app can alert anyone they’ve been in contact with without revealing who the carrier is. In this way, the entire system is private, secure, and safe. Your data is locked up, infections are locked down, and we solve the pandemic and reopen the world. Great! So what’s the problem?

Not everyone is happy with this solution. Some health experts say the privacy protections go too far. For example, the practice of contact tracing usually allows public health professionals to build a map, including modes of transmission—that is who had it when and where and who they gave it to. But with the ultra-private method prescribed in the Apple-Google approach, that isn’t possible. It doesn’t let apps gather location data, so they can’t build an actual map of infections.

The Apple-Google approach was also slow to launch: many government health departments had finished their apps before the announcement was even made. At the time of this writing, no contact-tracing apps employ the Apple-Google method, and only three states in the US have agreed to adopt it: Alabama, North Dakota, and South Carolina. More states may choose to implement the system soon, but others have chosen to go their own road. Utah’s app does collect location data, and still others, like Iowa, have made no mention and seemingly no effort toward an app at all. In the US, we find ourselves in an odd situation where apps designed by trusted public health officials actually do less to protect user privacy and security than apps designed by corporations. If you’d asked me a month ago who I trusted more with my personal data, the Utah Department of Health or Google and Apple, I would have gotten the answer wrong.

What Does the Privacy vs Public Health Debate Mean for You?

Unfortunately, none of us has much control over how or if our states’ particular public health institutions choose to implement a contact-tracing app. But you’ll still be able to choose whether or not to use the solutions your state ends up providing. In my opinion, the Apple-Google interface is surprisingly well thought out, and the states that choose to use it will be committing to an acceptable level of user privacy, while providing a potentially life-saving service.

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Author Details

Cullen Thomas's picture

Author Details

Cullen Thomas

Cullen Thomas is a Writer and Producer at iPhone Life, creating tips and guides to help users unlock the full potential of their iOS and iPhone. In addition to writing countless tip-of-the-day articles and many detailed guides, Cullen has spent nine years as an instructor in media and communications at Maharishi University, lecturing on technical and artistic subjects ranging from camera and audio hardware to story-plotting to how to manage a film crew. Cullen answers questions daily about iPhones and iOS as part of the Ask an Editor insider service, and designs curriculum for iPhone Life’s online classes. As a frequent contributor to iPhone Life magazine and occasional guest on the iPhone Life podcast, Cullen likes to talk about security and privacy news, tech, gadgets, and apps, even if nobody asked.

Cullen holds a master’s degree in Cinematic Arts from the David Lynch School of Cinematic Arts. Cullen also holds two Bachelor’s degrees from Maharishi University, one in literature with an emphasis in writing and the other in Communications and Media. Cullen’s short fiction has been featured in anthologies from Amphibian Press and TANSTAAFL, and Cullen co-owns a game design company, Thoughtspike games, which builds thought-provoking puzzle games. Cullen is a sci-fi author, a coffee connoisseur, and an iPhone expert.