You give workers 1000 syringes and needles to vaccinate a village and they just use the same one over and over again.
The remainder are resold.
This was obviously happening in the AIDS transmission in Africa.
Of course there still could be many cases caused by contact with bodily fluids, sexual intercourse or eating bush meat.
Anyway, keep making and taking your homebrew colloidal silver for all the pathogens you might come into contact with.