As more governments turn to tracing apps in the fight against the coronavirus, a deep-rooted tension between the need for public health information and privacy rights has been thrust into the spotlight. Track-and-trace technology is being touted as a silver bullet that will allow economies to reopen and people to emerge from home confinement, with health authorities keeping tabs on the virus’s spread. But many fear personal data gathered by governments or companies in the name of pandemic control will be abused for political or commercial gain, or outright oppression in authoritarian states. “If we are not careful, the epidemic might mark an important watershed in the history of surveillance,” Israeli historian Yuval Noah Harari wrote in The Financial Times at the height of the coronavirus outbreak. While fast-improving technology may be a welcome aid for public health officials caught off guard by the scale of the coronavirus crisis, the “downside is, of course, that this would give legitimacy to a terrifying new surveillance system”, Harari argued. Many countries have already introduced smartphone apps to track people’s infection status and movements with the intent of alerting people who may have been in close contact with a carrier of the virus. In some countries participation is voluntary, but in many it is not.