This Viewpoint compares manual and digital strategies for coronavirus disease 2019 (COVID-19) contact tracing, describes how countries in Asia and Europe have used smartphone tracking, and discusses privacy and discrimination concerns and strategies for balancing public health and civil liberties in the US.

The authors note that the best uses of digital (e.g., smartphone) technologies augment, but do not replace, manual tracing. They point to successful strategies in Maryland, Massachusetts, and New York that have massively scaled up manual tracing approaches by automating systems. However, they also find value in digital tracing approaches to significantly contribute to curtailing the spread of SARS-CoV-2 infection if adopted widely and integrated into comprehensive public health strategies. The discuss an Apple-Google system that could rapidly notify smartphone users if they have been in close proximity with a person medically diagnosed with COVID-19. They believe that it is important for public health agencies to have oversight of such systems, and note that the voluntary nature of downloading and using this type of smartphone application means that widespread uptake will be required for the system to be most effective.

They also discuss two contrasting approaches to digital contact tracing: a more centralized approach favored by governments in China, South Korea, Taiwan, and elsewhere and a decentralized, user-centric approach supported by the joint Apple-Google system and favored by some, but not all, European countries.

In their opinion, the optimal design for a digital tracing system could balance health and privacy. They believe that digital tracing should augment traditional public health strategies but not replace them.