I had a good 10 years of more without ever getting a cold. I think sometimes a virus hits the lymphocytes (a type of white blood cell whose job it is to fight viruses) and makes the immune cells that attack your myelin (also lymphocytes in my basic and unscientific brain) go into overdrive. So instead of a cold you get either an MS relapse, or silent attacks on the myelin, where there’s inflammation, but not necessarily symptoms.
Shoot me down if you have a real sciencey type of solution. Meanwhile, I’ll stick to my anti-nerd answer.