This is a concern to me too. While I could simply find that the zapper worked, easily killing many microbes, the failure of the zappicator to work pushed me further into questioning why.
The circuit itself is incomplete and from my perspective it does not create enough electro-magnetic power to accomplish much of anything.
I can conceive of one possible effect. Due to the small amount of energy produced, perhaps it might be just enough to notify the immune system of a possible threat?
Perhaps there is something missing from Dr. Clark's diagram as there was in some of her early zapper diagrams?
We need more study on this. I challenge anyone with a zappicator to run tests as I have and to post their results because in actuality, I would love to see the product work.