The Body Guardian
The thick sticky mucus in your nose lining traps viruses and other foreign particles before they enter the lungs. That’s good.
Generally, dust, pollen and other particles can be swept into the back of the throat to be swallowed and killed by stomach acid. Also good.
Sir William Osler, a Canadian physician who advanced medical science by putting students into both clinical and lab work, said that sometimes virus particles ride the tiny hairs from the nose into the “garbage dump" in the back of the throat. There, the miniscule invaders glom onto body cells a thousand times their size and hitch a ride, pretending to be something they are not. They fit like a lock falling into a key, adjusting themselves into the ICAM-1 receptors and docking there to begin their havoc.
If you are lucky enough to have had this strain before, protective antibodies will guard against it. The antibodies neutralize the viral particles by binding to their surface and hampering their ability to slip into a cell and release a piece of itself into RNA or genetic material.
However, viruses’ only goal is to multiply. They depend on an organism’s host to replicate. They have no cell; they are acellular. When attacked and hitched, so-to-speak, the body cell starts to destroy itself and fresh virus particles release to infect surrounding cells.