As the world continues to grapple with the Coronavirus pandemic, health officials are relying on a tried-and-true method of limiting the spread of the potentially deadly disease: contact tracing. Figuring out who has been close enough to an infected person long enough to catch the disease, then taking steps to prevent those people from passing it to others, is a method that dates back to the 1920s, when health authorities used it to rein in the spread of syphilis. In the era of smartphones, it seems only natural to add a technological dimension to contact tracing.
Using smartphone apps for contact tracing raises questions, though. For one thing, it is not entirely clear how effective that is; the answer depends on both how well a smartphone can measure contacts and on how many people actually decide to use the apps. Perhaps the chief concern, though, is privacy. How do you design a system that identifies who has been in contact with whom without giving all sorts of personal information to governments or data thieves that might abuse it?