Exactly - I have huge respect for Bruce Schneier when it comes to matters relating to cryptography. But apart from commenting on the security, privacy and other

Exactly - I have huge respect for Bruce Schneier when it comes to matters relating to cryptography. But apart from commenting on the security, privacy and other technical aspects of these apps, I'm not sure on which authority he's giving these opinions on matters relating to epidemiology. At very least I'd like him to give some supporting scientific citations. But as it stands, Bruce's opinion on the medical and public health efficacy of these apps is no more valuable than yours or mine.