i remember some time back reading about some virus that was infecting abbatoir workers who were killing pigs using a device that caused a blood spray in the air they specifically said that it was because it got in their eyes and thereby transited into the blood respiratory viruses generally transit via goop that you have spat on something and then someone touches that goop onto a mucus membrane, usually the nose, it can be the eyes too, but that takes a LOTTA snot getting in your eyes to transit effectively the virus has a narrow time window as well, because the moment your immune system starts to notice something it has whole range of responses that make further exposure less effective, enzymes that break its attack vector and so forth the virus doesn't survive long without replication, so the main way you incubate colds and flu viruses is with limited ventilation indoors with infected people spitting into the air, this is why coughing is one of the most common vectors, sneezing less so because sneezing tends to be heavier and drier and once the virus is dehydrated its chances of transit are nearly zero, it will be wrapped in a coating of dried snot at that point