My colds were always preceded by a sore throat. Provided the gargling was done before the first tickling at the back of the throat, the soreness disappears and the cold does not develop.
I have kept this secret because I realize that if this remedy was adopted universally, thousands of cough mixture employees would be thrown out of work.
However, now in my mid nineties, I feel it is my duty to reveal this cold cure, rather than carry it to the grave.