A rather large disconnect between what I hear from medical side and how people act seem clear. The medical officials all say for the most part the general population, other than those infected, don't benefit from wearing the masks.
In part that is due to improper use. I discount that because I've seen too many pictures of the medical response staff wearing masks that simply cannot be ones that create a true, airtight seal.
The other part seems to be that the virus is not really an airborne infection but more about small droplets of human fluids which carry the virus. Hence the recommendation that those with the infection use the mask to limit how they are spreading it.
Still, infection is a random chemical reaction. As such your chance of contracting the infection is a function of likelihood of an individual virus (one individual protein group) times the number of viruses that entered.
Seems that as long as the probability of any given virus to succeed in infecting you is low, then anything one does to limit the number incoming would be helpful.
Granted, there may well be a large number, in absolute terms, in any micro droplet of fluid inhaled which might itself make the effort pointless. But has anyone seen any estimates or other data at this level rather than the more aggregate type data like R0 seems to be?