Benefits of Mobile Contact Tracing on COVID-19: Tracing Capacity Perspectives.

Abstract

For effectively suppressing COVID-19's spread, contact tracing has been widely used to identify, isolate, and follow-up with those who have come in close contact with an infected person (or “close contacts”). Traditionally, contact tracers in local health offices interview an infected person to identify visited places (or hotspots) and then check any close contacts. For the accurate recall of travel history, several countries including South Korea corroborate multiple data sources, such as cell location or credit card transactions (1). Beside this traditional approach, various mobile apps were introduced to help improve travel history tracking including automated GPS tracking (e.g., Israel's HaMagen) and manual place QR-code scanning (e.g., New Zealand's NZ COVID Tracer and Korea's KI Pass). Alternatively, mobile apps maintain individuals' “encounter history” (instead of place visit history) by leveraging peer-to-peer wireless beaconing (i.e., self-announcing its presence to nearby devices) with Bluetooth Low Energy (BLE) in smartphones, such as Google-Apple's Exposure Notification and Singapore's BlueTrace and TraceTogether. This encounter history can be used later to judge whether a user had a risky encounter with an infected person. We argue that traditional manual contact tracing can be greatly improved by leveraging the wisdom of crowds. Local community members install mobile apps to self-collect “breadcrumbs” for contact tracing, such as GPS traces, place QR-codes, and wireless encounter histories, which can offer near real-time assessment (2). However, there is a systematic lack of adoption of mobile apps in many countries, and success stories of mobile apps are scarce. This is partly because local health authorities are unsure about the benefits of mobile apps, mostly worrying that a lack of app adoption fails to achieve digital herd immunity (3). We emphasize the importance of adopting contact tracing apps via “contact tracing capacity modeling.” Our model clearly demonstrates that the adoption of contact tracing model apps can potentially increase contact tracing capacity. Furthermore, this capacity increment thanks to crowd participation will greatly help local authorities to better handle confirmed cases in the early or late phases of the pandemics. In the following, we present our approach of contact tracing capacity modeling and its benefits for contact tracing. We then discuss practical challenges related to application adoptions by citizens and health authorities as well as technical implementation issues.