VAPOUR & VAPING.
When we sneeze, in addition to the visible spray, we also eject ultra-small particles of liquid.
Whether or not we have an infection, both the spray and the microscopically small particles contain bacteria and viruses from our respiratory system. These "bugs" can survive until such time as they run out of water or are killed by ultra violet radiation etc.
If someone else breathes in these particles, some will lodge in that person's respiratory system, and unless dealt with by the immune system will spread an infection. This much is common knowledge.

Now let's consider how a vape works:-
A small amount of water is subjected to ultrasonic waves, causing it to break up into a mist of minute particles, similar to mist or condensed steam. However, unlike the former two it never passes through a gaseous state. Therefore, any "bugs" in the water remain live.
Provided the water used is pure and sterile, this is not a problem, but if non-sterile additives are also used, the final vaping fluid mixture could carry "bugs" and be detrimental to the vaper's health.

However, there's another consideration:-
The vaper inhales this mist, then exhales it, usually quite strongly, and often in a form of "display". ("Look at me - I'm vaping!" ) (I've yet to see an apologetic vaper.)
This mist, as it passes in then out of the vaper's respiratory sysyem, supplies microscopic "life-rafts" for viruses and bacteria.
If the vaper is reasonably isolated from others, no harm is possible, but in a crowded room, any infection will be spread far more easily than if the carrier were not also vaping. For this reason, I feel that indoor vaping should not be allowed in public.
Thoughts??