The common cold is spread from one infected person to another, according to WebMD. The contagion spreads through contaminated surfaces and through droplets of secretions from an infected person who sneezes.
When the cold virus latches onto the nose or throat lining, white blood cells are dispatched by the immune system to attack it, according to WebMD. If the virus is of a strain that is new to the body, the first effort by the immune system is rebuffed, and more white cells are sent out. This causes familiar cold symptoms, such as inflammation and copious production of mucus. As the body works harder to fight the infection, the cold sufferer becomes fatigued and feels poor.