On the privacy-conscientious use of mobile phone data (2018)
nature.com
nature.com
A relevant chat on virus tracking apps: https://www.youtube.com/1hKwDdBQN04
Paraphrasing:
>In the case of a pandemic, any entity collecting private user tracking data, even if they distribute that data anonymously to alert a user that they have been in close contact with an infected person, can de-anonymise that data.