Rolling out an app without considering its wide ethical and social implications can be dangerous, costly and useless. For example, bluetooth signals that show the proximity of two individuals’ mobile phones are not a certain indicator of infection risk — two people might be in the same space but physically separated, for example, by a wall. A high level of false positives from such an app (for instance, as a result of self-reporting) could lead to unjustified panic. The public might reject apps that breach principles of privacy, equality and fairness. This would frustrate the efforts and waste the resources being invested in developing and deploying such technology.
Another point is that contact-tracing apps should be available and accessible to anyone, irrespective of the technology needed or their level of digital literacy. Yet many apps work only with certain phones.
There are many approaches.
Here you find the full article about ethical guidelines for COVID-19 tracing apps.
> How to find out if contact-tracing apps are ethically justifiable?