The coronavirus has people freaking out about toilet paper, which may seem a little odd. It's a little easier to understand the run on hand sanitizers, which are now hard to find on store shelves. But the CDC and others are emphasizing a key point: Hand-washing with ordinary soap and water, for 20 seconds, is actually better than using hand sanitizers when it comes to COVID-19. The following explain and amplify the point:
- CDC guidance: The Centers for Disease Control and Prevention "recommends washing hands with soap and water whenever possible because handwashing reduces the amounts of all types of germs and chemicals on hands," reads the CDC advisory. "But if soap and water are not available, using a hand sanitizer with at least 60% alcohol can help you avoid getting sick and spreading germs to others."
- Agreement: "Sanitizer might feel like a modern-day, scientific, and more clinical upgrade to soap," writes Brian Resnick at Vox. "But I'm here to tell you that soap—all sorts of it: liquid, solid, honeysuckle-scented, the versions inexplicably only marketed to men or women—is a badass, and even more routinely effective than hand sanitizer. We should be excited to use it, as much as possible." His piece is based on an interview with Palli Thordarson, a chemistry professor at the University of New South Wales.
- Why? The CDC runs through a number of reasons why this is so, including: "Soap and water are more effective than hand sanitizers at removing certain kinds of germs, like Cryptosporidium, norovirus, and Clostridium difficile. Although alcohol-based hand sanitizers can inactivate many types of microbes very effectively when used correctly, people may not use a large enough volume of the sanitizers or may wipe it off before it has dried."
- Scientist's explanation: The above-mentioned Thordarson put up a Twitter thread explaining what's going on here, which involves the chemical nature of soap and how it interacts with the virus. At the Guardian, Gaby Hinsliff boils it down: "The virus is a self-assembled nanoparticle in which the weakest link is the lipid (fatty) bilayer. Soap dissolves the fat membrane and the virus falls apart like a house of cards and dies—or rather, we should say it becomes inactive as viruses aren’t really alive." Or as Thordarson puts it to Vox: Soap "is almost like a demolition team breaking down a building and taking all the bricks away."
- A how-to: So, yes, to recap, use soap and water often—or use hand sanitizer with at least 60% alcohol when you're not near a sink—but it also matters that you wash your hands thoroughly for 20 seconds. And you've got to hit everything: The Wall Street Journal has a video tutorial.
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