The concept of the transmission immune system hard at work to protect potential hosts transforms our understanding of airborne disease transmission. It’s an active process.
The respiratory trace is coated and protected by a thin layer of mucus. This is constantly secreted and moved by cilia like a conveyor belt towards the throat where it’s emptied into the stomach. Any respiratory system targeting pathogens trapped in the mucus are no longer a threat. This process is termed mucociliary clearance.
IMPORTANT: to prevent infection the host doesn’t need to “kill”, as in permanently destroy the virus. Instead, they just need to surround pathogens with protective mucus, so when the aerosol impacts the upper respiratory tract of the potential new host, it doesn’t come into contact with the vulnerable epithelial cells beneath.
The dehydrating process of mucus aerosol is probably an integral part of this process, exactly how this works is unknown, but we do know that mucus forms cage like structures to prevent the “random walk” of the virions they contain. Just as mucus is known to bind to pathogens in the respiratory tract, it would also bind to virions in aerosols.
Virus transmission could be understood as a race between the virions to get inhaled and the dehydrating mucus to immobilize the virions…
Temperature and humidity would be critical variables in determining transmissibility, but it takes time for a puff of infectious exhaled air to disperse, for the air to mix, for the aerosols to start evaporating and demobilising the virions they contain.
But there is a much faster way to trigger and power this process. Which would be to use… …sunlight.
“Wait?! What? I have questions!” I hear you ask… well then, let’s continue.