This is the key fact. Only 2% of the subjects tested antibody-positive at the end of the study (low enough that it's near the false-positive rate of the home an

This is the key fact. Only 2% of the subjects tested antibody-positive at the end of the study (low enough that it's near the false-positive rate of the home antibody tests). The mask group had fewer cases (by PCR, they had zero). But the numbers are too small to say. If you ran the study in the US in the same time period, you would have had a better shot.