Here's the annual article pointing out that Vitamin C and Echinacea won't prevent or reduce the symptoms of a cold. You'll have to suffer through it, take a day off, blow your nose, and watch daytime TV like everyone else.
Next time you're afraid you might get sick, don't bother with Airborne or Emergen-C or some other bullshit preventative elixir. Do what science tells you and look at pictures of sick people.