Most colds are transmitted through hand-to-nose contact; alcohol-based hand sanitizing gels and sprays reduce the potency of most viruses within seconds, and so provide a good defense — as long as you keep some handy.
This is the first sanitizer I’ve found that’s not only fits easily in my small purse — or clips to a pocket — but is also refillable. The top unscrews, and you can refill it with 70% rubbing alcohol (use ethyl alcohol; less stinky and not as drying as isopropyl). Sprays are more useful than gels, as they can also be used on questionable restroom fixtures, for example. I’ve seen 1 or 2 ounce spray bottles, but those are usually about 1 1/4 inch wide. This one is the size of a slender highlighter, slightly thicker than a standard pen (at its widest, the barrel is 5/8 inches—not counting the clip—and 5 inches long). It fits easily, even in my inky-dinky overfilled purse, and when I have a cell phone or PDA in my pocket along with the bottle, things don’t get uncomfortably bulgy. I’m a pharmacist, exposed to every cold virus that comes down the pike, and I haven’t had a cold in a year. Dunno if it’s the spray or dumb luck, but I used to get them pretty regularly before I developed the habit of spraying my hands after any exposure to a suspiciously sniffly customer.