This is only a theory, but I believe the physical principle behind saline spray is that because it is a supersaturated saline solution, the saline solution is absorbed by osmosis through the cellular walls of a virus cell, thus either killing the virus cell or preventing its ability to reproduce.
similar results are obtained by taking raw apple cider dissolved in water. Acidifying the blood over a period of hours, makes the cell walls of virii and bacterium very vulnerable... and reproduction, far less likely.
Most americans NEVER drink enough fluids to stay well.
8-10 glasses a day of water. NOT diet pepsi, not beer, not wine, not coke... but water. WHAT you drink above and beyond that does not matter so much as the initial gallon or two of water.
one of many health problems we bring upon ourselves...
food that does not nourish and fluids that do not irrigate the system.
flu season makes it hyper critical we get it right.
A virion, i.e. an elementary viral particle, is composed of either a DNA or RNA core surrounded by a protein covering called a capsid. It has no cell wall. It penetrates another cell, bacterium, animal or plant cell, merges its core with its host's genetic material, and directs it to make more copies or the virus, often, maybe always, to the point where it literally bursts the host cell.
IIRC, the saline solution decreases the number of droplets(bioaerosols) formed during sneezing or coughing apparently by the effect on surface tension in the secretions of the respiratory tract.