March 12, 2020 | by: Chris

How soap absolutely annihilates the coronavirus

You’re not just washing viruses down the drain. Soap destroys the coronavirus; a chemistry professor explains.

As Covid-19 cases surge across the world, there’s one consumer product critical to our great national battle to “flatten the curve,” or slow the epidemic: soap. Humble, ancient, cheap, effective soap.

Respiratory viruses — like the novel coronavirus, the flu, and the common cold — can be spread via our hands. If someone is sick, a hand can touch some mucus and viral particles will stick to the hand. If someone is well, hands act like sticky traps for viruses. We can pick up droplets that contain the virus, and they’ll stay on our hands, and perhaps enter our bodies if we touch our hands to our faces.

That’s why our hands are the front lines in the war against Covid-19. The Centers for Disease Control and Prevention (CDC) recommends washing hands with soap and water as the top way to clean our hands. “But if soap and water are not available, using a hand sanitizer with at least 60% alcohol can help,” the CDC says.

The CDC prioritizes soap. Yet, per news reports, people have been stocking up and hoarding sanitizer. 

Sanitizer might feel like a modern-day, scientific, and more clinical upgrade to soap. But I’ll 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.

That’s because when you wash your hands with soap and water, you’re not just wiping viruses off your hands and sending them down the drain. You’re actually annihilating the viruses, rendering them harmless. Soap “is almost like a demolition team breaking down a building and taking all the bricks away,” says Palli Thordarson, a chemistry professor at the University of New South Wales, who posted a viral Twitter thread on the wonders of soap.

The soap takes care of the virus much like it takes care of the oil in the water. “It’s almost like a crowbar; it starts to pull all the things apart,” Thordarson says.

One side of the soap molecule (the one that’s attracted to fat and repelled by water) buries its way into the virus’s fat and protein shell. Fortunately, the chemical bonds holding the virus together aren’t very strong, so this intrusion is enough to break the virus’s coat. “You pull the virus apart, you make it soluble in water, and it disintegrates,” he says.

Then the harmless shards of virus get flushed down the drain.

The trick is this all takes a little time to happen, and that’s why you need to take at least 20 seconds to wash your hands.

First off, your skin is wrinkly, and it takes time for soap to penetrate into all the tiny folds and demolish the viruses that lurk within. Then the soap needs a few moments to do its chemical work. “You do need a bit of time for all the soap to interact back and forth with the virus particle,” he says. Twenty seconds should do the trick just fine.

Alcohol, the main ingredient in hand sanitizer, can destroy viruses, too. Sanitizers “actually work in a similar way, the alcohol molecules are somewhat amphiphiles,” he says. The thing is, you need a very high concentration of alcohol to achieve the same effect. (Chemicals called quaternary ammonium compounds — the main ingredient in Lysol — kill viruses too but can be a bit harsher on the skin.)

The CDC recommends a sanitizer that’s 60 percent alcohol, so beware of sanitizers or wipes on the market that don’t meet this standard (or contain alcohol at all). Hand sanitizer is useful, but it can fail in un-ideal situations. If your hands are wet or sweaty when you use the sanitizer, that can dilute it and diminish its effectiveness. Also, sanitizer doesn’t clean your hands of sticky grease to which viruses can also adhere.

“Soap doesn’t really fail easily,” Thordarson says. It doesn’t really matter the formulation of soap, either. You don’t need “antibacterial soap” — which the Food and Drug Administration advises to skip altogether due to a lack of evidence of its usefulness. And you don’t need a super-harsh detergent like you’d put in your dishwasher or laundry machine. Simple soap works fine. “As long as you give it a little bit of time, it will do its job.”

Story: Brian Resnick