"Contact tracing is made of people and there isn't an app for world-historical level of care work it requires," as Dan Greene said on Twitter.

"Successful contact tracing involves patiently helping people recall with whom they have interacted in the preceding weeks and assessing the risk associated with each of these interactions.
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Most problematic, however, is assuming that locating people is all that contact tracing requires. To succeed, contact tracing programs require that people trust the entity to whom they are reporting. Trust is built on empathy, patience and the ability to help someone who has just been exposed to a life-threatening disease. Human contact tracers need to guide a rattled parent to think through who their child might have played with at a neighborhood potluck a two weeks ago or an undocumented immigrant find support and care should they fall ill. They also need to understand and help people marshal the resources they will need to sustain a 14-day quarantine after they have been exposed. Thus, contact tracing hinges on deeply human exchanges. There is no app for that.

Digital technologies do have a role to play. They will be crucial to successful contact tracing programs. But they must be intentionally built to assist, rather than replace the people in the health care loop vital to success."