Associate Director of Epidemiology IQVIA Frankfurt am Main, Germany
Background: The COVID-19 pandemic catalyzed innovation in infection control measures, including the widespread deployment of wearable- and phone-based digital contact tracing systems. However, these technologies were complex for the public health community to implement, hampering effectiveness in many settings.
Objectives: To provide an overview of existing digital contact tracing systems, explaining how they work and creating a framework for understanding design elements that impact their effectiveness as public health tools.
Methods: Scientific literature and publicly available information from relevant health authorities and other stakeholders was reviewed. Information was synthesized to develop a conceptual framework explaining how design elements work and highlighting opportunities for future improvement. Special attention was paid to data collection (i.e., from wearables and apps) and opportunities for real world evaluation of systems.
Results: A range of digital contact tracing interventions were deployed by governments worldwide and several closed-cohort occupational settings, including sports leagues. Key design elements of the systems include: (1) data architecture (i.e., centralized versus decentralized systems, impacting privacy guarantees and data availability); (2) proximity detection technology (e.g., type of phone- or wearable-device signaling); (3) alert logic and timing (e.g., 15 minutes at 6 feet, affecting the sensitivity and specificity of alerts; real-time proximity alerts and/or bidirectional contact tracing, determining scope of infection prevention); (4) population (eligibility and availability); and (5) the structural and public health context of the intervention (e.g., availability and timeliness of testing). Several systems showed evidence of substantial effectiveness in preventing transmission during COVID-19, though numerous limitations were also documented including limited adoption, imprecise estimates of proximity, and insufficient data collection to evaluate efficacy.
Conclusions: Digital contact tracing systems have the potential to mitigate the economic and public health impact of future infectious disease outbreaks, reducing community transmission and detecting potential cases early in the disease course. Lessons learned from solutions deployed during the COVID-19 pandemic provide an opportunity to improve multiple aspects of these systems and enhance preparedness for future outbreaks, including continuous data collection and linkage with core public health data sources to facilitate opportunities for real world evaluation.
