These (different) survival rates should have been discussed at the time as one of the determining factors in Europeans' decisions to make deals or not with the Natives.
You are wasting our time with all these information since the real question is: was it our duty to research all the effects of virus sooner than what historically we have done.
Having the intention of implementing a biological attack is almost as reprehensible as launching it.
Concerning the face-to-face transmission, it is not the Natives who insisted on meeting the whites.