What feature of the virus does the anitgen test detect? If this one has so many mutations, it's not a ridiculous question.

I don't know the answer, but related: I read the manual that came with the new self tests and it mentioned what else it reacted to, like some micrograms of influenza type such and such. There was a whole host of things it responded to. They seem to just detect extremely broadly. Previous self tests didn't include this, I found it quite interesting.