Contact is far more likely cause of infection, agreed. But when sneezing we spray a tiny amount of fluids. Are they not enough to get infected even with a low probability? Given an high number of occurrences any low probability yields an event.
The virus still has to be in nasal passages or perhaps lower to get in what's expelled. Here's what I said in a recent discussion in reference to the fear it would evolve to be "airborne" as the term is medically used (https://news.ycombinator.com/item?id=8421982):
The critical distinction here is that Ebola doesn't seem to infect the outer part of the respiratory system like colds or influenza. There's not a huge mass of cells there to be shedding viri and getting into the air, and it would take more than a few mutations for that to change.
Ebola viri have been found in saliva, tears, can come from bleeding in the respiratory system, so it obviously can get airborne that way. Exactly what that means (how big are the droplets, how long do they stay in the air etc.), how significant that is as a mode of transmission (which includes iffy estimates of how many viri (virus particles) are required to make an infective dose) ... we just don't know. But with our current Ebola importation policy, it's very likely we will start to get answers to these questions....
That's the definition of "aerosol transmission" here.
Depending on the drop size and the viral load in those drops, depends on how far it will travel in air, how long it will be suspended in air, what potency it has, and how likely someone other can get infected when it's inhaled.
"The common cold virus is typically transmitted via airborne droplets (aerosols), direct contact with infected nasal secretions, or fomites (contaminated objects)."
A person with Ebola going through a crowded airport and sneezing could infect dozens of other people under the right circumstances (virus strain, load, etc).
Because this is actually a fairly well defined area of research. Sneezing absolutely does produce particles that small. Ebola cannot be transmitted by those particles. The larger droplets that can transmit Ebola are too large to make it through a ventilation system.
> Although they are not naturally transmitted by aerosol, they are highly infectious as respirable particles under laboratory conditions.
I think the issue is to what degree it can get into the fluid that is sneezed out by humans... Once it's in it, the size of the droplet does not matter to how viable the virus is - it's deadly if inhaled in by someone else.
