Speaking from my point of view as a one-time history student, it has been used in the past. I can't give you any judgment on whether or not it's effective and how we contain the virus.
What I'll state is that we, at Google, are certainly an environment where we're recognizing that we need to modify our services and provide tools to public health authorities so that they can explore options. We are recognizing the opportunity and then trying to react to it in a constructive way, while recognizing our obligations to the users.