Fig. 1.

Geo-surveillance of an individual's daily trajectory. On the left, a smartphone's GPS receiver, cell phone tower signals or Wi-Fi connections can be used to track and collect data on people's daily trajectories. Coupled with other data, such as COVID-19 infection status, trajectory data can be used to identify the recent locations of infectious patients and warn others who were potentially exposed at these locations to self-isolate. On the right, Bluetooth technology can be used to identify individuals who have come in close proximity to each other. While the use of this technology does not allow identification of the location of these users, it can track users who have come into close contact with each other. Coupled with other location data, such as GPS or the use of cell phone towers, Bluetooth technology can play an important role in identifying if individuals have come into close contact with someone infected by COVID-19.