This study argues that manual contact tracing would be insufficient for containment and that we need to consider apps and such. The ethical issues are discussed.

When we begin to re-open again, and leave social isolation, we will need to be able to do contact tracing and isolation. Preventing further transmission is a top priority. Researchers in this study analyzed key parameters of epidemic spread to model the contribution of different transmission routes and determine what would be needed to do case isolation and contact-tracing properly.

They found that viral spread is too fast for manual contact tracing. It could, however, be controlled if contact tracing were faster, more efficient, and at scale. A contact-tracing App which builds a memory of proximity contacts and immediately notifies contacts of positive cases can achieve epidemic control if enough people agreed to use it.

The ethical issues for an intervention of this kind are real. But we need to find a way to control spread without need for mass quarantines.