As I responded to the sibling comment, I don't think that is accurate. Of course many, if not most cases can not be traced, many certainly can be. Some people know exactly where they got covid, and who they exposed, and where.
The US has 50,000 full time contact tracers working to collect this information. Surely there is some data by now?
>Your questions are unanswerable.
IF the question is categorically unanswerable (which I don't believe), contact tracing programs should be disbanded.