This is an interesting topic to me and I have spent a bit of time studying it.
I have zapped a number of human cells under the microscope and they are not badly affected. It appears to me that it is the cell walls and rigid cell membranes that are present in microbes but not in higher organisms that is affected. I believe that zapping also breaks apart the capsids in many virus forms.
There is much more studying that is needed but sadly, I do not have enough money or time to accomplish all that I need to do.