[Goose]

Undoubtedly there are more out there, as proving this with genomic sequencing requires the effort of a motivated researcher or clinician. Another was pubbed this AM, so now we have two in the US. 

But again, we're 8 or 9 months into this. If reinfections were common, we would know it.

Agree with that. It certainly can happen, but it isn't so common that it is obviously happening. One (of many) unanswered questions is how common are reinfections with the "same" strain of the virus. It makes sense that a virus that has mutated may not be defeated by antibodies that act against a now somewhat different set of antigens. It is also probable that some(very few)  people lose their immunity even to the same virus. As a general threat to society, this is important in that it preserves the disease in the population so that people without immunity can get it.

[Goose]

Undoubtedly there are more out there, as proving this with genomic sequencing requires the effort of a motivated researcher or clinician. Another was pubbed this AM, so now we have two in the US. 

But again, we're 8 or 9 months into this. If reinfections were common, we would know it.

Agree with that. It certainly can happen, but it isn't so common that it is obviously happening. One (of many) unanswered questions is how common are reinfections with the "same" strain of the virus. It makes sense that a virus that has mutated may not be defeated by antibodies that act against a now somewhat different set of antigens. It is also probable that some(very few)  people lose their immunity even to the same virus. As a general threat to society, this is important in that it preserves the disease in the population so that people without immunity can get it.