 Hi, I'm Jonathan Zitron. I teach on law and computer science at Harvard University, and I'm a director of its Berkman Klein Center for Internet and Society. And in this video, I just want to get some terms straight around contact tracing. The World Health Organization defines contact tracing as identifying, assessing, and managing people who've been exposed to a disease to prevent onward transmission. I realize that word managing might sound a little ominous, but really what it's talking about is having people be in a position to know that they are infected and could be contagious, even if they're not yet showing symptoms, so they wouldn't naturally maybe self-isolate. And if it turns out you've tested positive, the ability to know that soon and to be able to find out who you've been in touch with during the window in which you might yourself have been contagious. And once you do that, that contact tracing allows those people that you've been in touch with to themselves be notified that they could be exposed and to let them quarantine so that they're not further exposing others as they wait to see whether in fact they've come down with the illness that you might well have shared with them. Contact tracing in its traditional forms involves interviews. And this also might be why you've seen in the United States news of the standing up of, according to a Johns Hopkins study, up to 100,000 new workers who will be contact tracers working for states, counties, and cities, their health departments doing these sorts of interviews. Now is it necessary to do this? You might be about to find out. If you look at any of the plans for reopening the United States in the spring of 2020, these plans all contemplate testing, tracing, and quarantine as a key pillar. And the White House plan for reopening has as one of its three sets of core state preparedness responsibilities, testing, and tracing. Now the traditional interviews that I was just mentioning, they rely on imperfect human recollection in order to figure out where somebody's been and who they've been in touch with. And those interviews also involve really specialized work and handling sensitive data. And right now, it's hard to scale up all of the contact tracers we would need, able to handle that data sensitively to figure out the right survey instruments and how to offer the kinds of services that they can. And that's why we also now start hearing about digital contact tracing, a subset of case management tools. Case management tools can be something as basic and boring as the software that a contact tracing professional might use to keep track of all the people they're calling, what those people are telling them, who needs to be called next, where the follow-ups are. And there are contracts out by many of the states and municipalities engaging in contact tracing to have that kind of software at hand. There's a second form of digital contact tracing assistance tools that involve possibly using your smart phone in some way in order to be able to say that data that this phone is gathering as you walk around in the world could really help either by some lights, substitute for, and by many others, simply be a helpful input to a compliment to the kind of interviewing that we expect to happen when digital contact tracing happens. And a big question, definitionally here, is to what extent will the data on that phone be used as GPS or geolocation, absolute location data? If the data on the phone can tell you where you have been at various times during the day, during the past few weeks or something, that's the kind of thing that would really help a contact tracer help you jog your memory. Oh yeah, I went to the store on Wednesday, not Thursday. Or, oh, I remember I was on the highway at that time and so anybody I was near, no problem because I was in the car, I was inside, I was outside. These are all things that can affect the transmission of COVID-19 as a disease and it might be material. Now there's a catch because a lot of the contact tracing apps that we've seen made available to people, some of them seek to use geolocation data, others don't. And one reason is because Apple and Google have come up with a framework. A framework that they are wanting apps to be able to tap into on Android phones or iPhones that will use a neat, clever trick to figure out who has been near whom without needing to know where anybody has been. And the parlor trick, the rabbit in the hat, is more or less something called BLE, Bluetooth Low Energy. And this is part of newer iPhones and Android phones that has the phone able to send out a small beacon, a kind of RSSI, a received signal strength indicator from one Bluetooth beacon to another that can say, oh yeah, I've been within 6 feet or 12 feet or something of another beacon, another phone for example, whether or not I know the person who has that phone or whether or not our phones have talked to one another. And the idea is that apps could be written to tap into that Bluetooth Low Energy so that you would know when your phone has been near another or more important, your phone would know. And should you test positive and be able to certify as much to an app on your phone with the assistance of the Public Health Authority, that phone would now be able to send a cascade of notifications out to people meeting that certain threshold for thinking that their phone has been near your phone within a particular period of time. Now the catch is that for privacy reasons, Google and Apple's framework does not contemplate the use of any location data. So it'll tell you that you have been near another phone and tell the owner of that phone without telling you who it is that your phone has been near their phone and they don't get told who you are either. They then have a chance to call their health department and say I think I've been exposed. But no other data other than that proximity is used to do it and the database itself is basically distributed among all the phones. Now that's great from a privacy perspective. It does tend to make for trouble if what you want is the more fulsome data that a contact tracer doing an interview would use to say, oh, I see you've been proximate to this other person, but that's because you're an apartment building and they're on the floor above you or below you. So that's no problem. You're not sharing any air between you and that shouldn't count as a contact. So these are some of the issues we'll see as we look at different app makers looking to make apps that can be helpful in tracing or an exposure notification. They're going to have to choose whether to use the Apple Google framework, which will only do this kind of cool proximity, or if they want to try to kind of freelance it on their own and make apps that might make use of location or other data on the phone, thereby though precluding them from using the special framework that Apple and Google have come up with. There's lots of other issues too, ranging from battery life on the technical side of things. If your phone is trying to figure out where you are all the time, that can lead to a lot of trouble in just using the phone for its normal purposes. And in the broader perspective, it leads to some issues around opt-in and voluntariness. For these sorts of apps to work to be linked to one another, even if the people don't know who one another are, it's going to be important for those apps to be installed on a lot of phones. And right now we're contemplating people going and downloading the right app and doing that. It might be that we need as many as 60 or 70% of the population to be using these apps, and not only that, but to have them installed and running days or a week or two before they're notified that they might be testing positive or have themselves been exposed and then wanting to use the data. Figuring out these sorts of issues, distributed versus centralized databases, the privacy dimensions, and trade-offs around what kind of data gets used and how it gets shared and how labeled it is, and how these apps are or aren't meant to integrate or able to be integrated with the traditional, interview-based, social work-based contact tracing kinds of activities that we see from the public health departments. These will be the subjects of the next video.