Mo...I hope that you are right in terms of B and efficacy in human trials. The link below is to another virologist who points out that even human lung cell lines are inadequate to recapitulate the complex structure of differentiated airway tissue. However, the point that epithelial lung cells are much more suited for these tests is not lost (as opposed to vero cells). The clinical trials with patients can't start soon enough and as you suggest, the selectivity index should be another indicator.
https://twitter.com/angie_rasmussen