Such a good question and I wish I knew.

As others have pointed out, the best way to get the spike bioweapon to the right victims is injection. It gets the right people infected (or venomed if that is the correct term ) and it avoids the cabal infecting themselves by accident, which is always a risk when deploying a bioweapon. Also, injecting a bioweapon gets past some of the body's outer defences and therefore evades part of the immune system and it's design.

Given all of this, I think injection is the best method, but this is an all-out assault on mankind and i'm sure they have other stressors to help such as money stress, poor nutrition and maybe other spike vectors to work in synergy with the injection of to affect the unvaxxed. Maybe those are infection-through-food, which is less effective than injection because it doesn't get directly to the bloodstream but may be used in adjunct.

I'm not convinced of nanite kill switches yet, although I did write a post a year ago about how 5G could act as a kill switch for the vaxxed. Here it is if you are interested https://greatawakening.win/p/15HIm5iDjh/sphinx-of-death-my-5g-theory/

I am ready to be convinced about other injected technologies used as kill switches but I need good evidence and I haven't seen enough yet.