7 Things You Don't Know About Colds

Remember that annoying cold you just couldn't kick last year? The one that kept coming back like a string of Nightmare on Elm Street sequels? Well, it was actually a series of different colds. After you're infected with a virus, you become immune to it, so it's nearly impossible for it to reinfect you. Unfortunately, you're still vulnerable to the 200-plus other viruses floating around during any given year, Collins says, and they can combine to create more than 1,500 different variations of colds. She explains that the first virus strikes a blow to your immunity (often compromising your vulnerable nasal passages) that makes you more susceptible to other viruses. You then touch something (or someone) germy and bring your hand to your face, or you get coughed or sneezed on, and you pick up a brand-new cold that's unrelated to the first. So keep up the hand washing, even if you’re already sick.