I never said all blacks are A and all whites are O.
Of course not. But I’m saying blood type might not might not be the place to look for a 7 out of 7 racial correlation.
I think I’d start with a social aspect. Did this group know each other, as by church, or even homeless encampment. Aside from race, what did they have in common.
We know blood type isn’t a strong enough indicator from Chines data. In a small dample it looked A types were slightly over represented in viris cases, but it wasn’t dramatic.