The Best Way to Kill COVID-19 Is Simpler Than You Might Think

Posted on April 07, 2020

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Did you know that viruses can remain active outside of your body for hours, even days? Disinfectants, liquids, wipes, and gels containing alcohol are all great at getting rid of them—but they aren’t as effective as what’s no doubt sitting by your bathroom sink right now: soap.

Health authorities have been sharing two main messages with us:

  • There are no drugs that can kill COVID-19 or help you get rid of it
  • Wash your hands like crazy

These statements might seem contradictory—there’s no cure at all, but a bar of soap is somehow my best defense? Why does soap work so well against COVID-19 when so many other things don’t?

The short answer is that the virus is a self-assembled nanoparticle, and its weakest link is its lipid bilayer. Soap dissolves this bilayer, causing the virus to fall apart and die or become inactive. Keep reading for the long answer.

How Viruses Work on a Cellular Level

Most viruses have three key building blocks: ribonucleic acid (RNA), proteins, and lipids. A cell that’s infected by a virus makes a lot of these things, which in turn self-assemble to form the virus. It’s important to note that no strong covalent bonds are holding these units together—that means you don’t necessarily need harsh chemicals to split everything up, which is the goal. When an infected cell dies, new viruses escape and infect other cells. Some of these end up in the airways of your lungs.

When you cough or sneeze, tiny droplets from your lung’s airways can fly up to 10 meters. The larger droplets are thought to be the main coronavirus carriers, and can go at least two meters. These droplets then end up on surfaces and dry quickly—but the virus remains active. Human skin, unfortunately, is an ideal surface for a virus. It’s organic, and the proteins and fatty acids in the dead cells sitting on the surface of your skin interact with the virus.

You can imagine the following order of events—you touch a surface with a virus particle on it. It sticks to your hands. You touch your face (especially your eyes, nostrils, or mouth), and you get infected. Most people touch their face every two to five minutes. That’s a lot.

How Soap Works to Kill COVID-19

Believe it or not, water actually does a fair amount in getting the virus off of your skin. However, it has a hard time combating the glue-like interactions between your skin and the virus, which means it isn’t enough on its own. Soapy water? Completely different. Soap contains fat-like substances known as amphiphiles—some of which are structurally very similar to the lipids in the virus membrane. The soap molecules, unlike water by itself, compete with the lipids in the membrane. This is also how it removes regular dirt from your skin.

The soap loosens the glue-like interactions, as well as the velcro-like interactions that are holding the virus together. You might be wondering, at this point, why plain old soap is more effective than say, hand sanitizer. Alcohol-based products contain almost all disinfectant products, usually containing high-percentage alcohol solutions (60-80% ethanol). So they kill viruses in much the same way soap does. The differentiator? A small amount of soap, when mixed with water, covers the entire surface area of your hands easily. On the contrary, you’d need to literally soak the virus in ethanol for a brief moment to have the same effect. So using sanitizing wipes or hand sanitizer on your hands doesn’t guarantee that you’re soaking every millimeter of skin on your hands well enough.

When you hear health authorities tell you to wash your hands, they really mean it. One of the best possible defenses against COVID-19 is found in a soap dish.

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