Ok sorry I was under the assumption that contact tracing was easy and accurate.In a situation like that it's likely impossible to trace back to find a "patient zero", but I just edited my post to add the stat that a few days ago 69% of the positive cases were in fully-vaccinated people.
So yes, it's not inconceivable that the vaccinated caught it from the unvaccinated.
-Rob
When I was told that no cases came out of peoples school district, they told me they knew this for sure because of contact tracing.