"Cure and eliminate all diseases by the end of the century": this is the ambition of Facebook boss Mark Zuckerberg and his wife, pediatrician Priscilla Chan, through their foundation, the Chan Zuckerberg Initiative. For several years now, the Web giants have been investing massively in the world of medicine. While Google is developing an artificial intelligence capable of competing with the best practitioners, Apple is allowing everyone to monitor their health thanks to connected objects, while Amazon is taking over the telemedicine and health insurance markets via Amazon Care, its assistance service. These tech behemoths are banking on the exploitation of health data, the "new black gold", to improve care, reduce costs and prevent illness. But can we trust them with this information blindly?