Soap vs. Hand Sanitizer: How They Work & Which is Best

Someone asked me the other day which is better at killing the coronavirus, soap or hand sanitizer. That’s actually the wrong question. So, while describing the difference, I realized a simple explainer might be helpful for everyone. This won’t take long (the long, sciencey explanations are in the links, with all the expert input and supportive research from the CDC and others).
How soap works
Regular soap, regardless the ingredients, is designed to separate dirt, grease and whatever else is on your skin from your skin. Soap doesn’t kill coronavirus. Its bubbles, along with vigorous scrubbing of all parts of your hands and fingers, lift viruses (and other germs) from your skin so they can be rinsed down the drain.
Scrubbing and rinsing are vital steps in the ritual. Two renditions of Happy Birthday, well, you know. But if you sing off-key, nobody really wants to hear that. Please instead just count one-thousand-one to 20.
For the record, it does not matter if you use hot or cold water when you wash with soap. If you’re not totally bored with hand-washing admonitions and the reasons why it’s so important, you can check out my deeper explanation on how it works and the fact that, wait for it… Only 5% of People Wash Their Hands Properly.
How alcohol-based hand sanitizers work
Hand sanitizers work in a different way, by exploding the outer coating of viruses (and who doesn’t want to explode some coronavirus right now?). These nasty germs, which technically are never really alive — they have to invade your cells to reproduce — become totally dead when you hand-sanitize them. Or at least that’s the idea.
The key is to use sanitizers that contain at least 60% alcohol, the minimum threshold at which they’re known to fly off store shelves.
Thing is, hand sanitizers are not as effective as proper scrubbing with soap and water (the CDC says so). 
In fact we don’t know exactly how effective the sanitizers are, because lab tests are typically done by companies that make hand sanitizers and the results are not made public, plus it all depends largely on whether you slather plenty on and rub it all over until it’s dry, per the directions. 
Even so, your hands will still be covered with grease and grime (and a bunch of hopefully totally dead coronaviruses). But yes, you can expect some level of protection (the CDC says so).
The dirty details on hand sanitizers, including how they’re tested and the importance of the 0.01% left behind even if your hand sanitizer “kills 99.99% of most illness-causing germs” as marketed, are in another story that dives deep into all this.
Bottom line
Hand sanitizer is useful in a pinch. If you’ve been lucky enough to score some. Just don’t let it make you overconfident that you’re germ-free. 
  • Keep your hands away from your face.
  • Don’t shake hands with others. 
  • Consider wearing a face mask if you must go to the grocery or other places where humans go, because coronavirus might be wafting through the air infectiously.
  • Distance yourself physically from others and touch stuff as little as possible when you’re out and about.

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