The Science of Handwashing

“Wash your hands.” This reminder has become as common these days as “Good morning” or “How’s the weather?”. But beyond the CDC’s guidelines for washing our hands, we’re still left with questions: How exactly does washing my hands prevent the spread of disease? Do I need antibacterial soap? How often do I need to wash my hands? Will this really protect me?

Let’s start first with why washing your hands is the best protection against the new coronavirus (and lots of other pathogens).

On average, we touch our face hundreds of times a day, most of the time without even noticing it. 

I’ve noticed recently that it’s almost a reflex, like when I’m thinking hard about something, a la Rodin’s famous statue “The Thinker.” We’ve all seen the nation’s leaders and top doctors broadcast updates every day this week and, despite their own warnings to “stop touching your face,” many can’t seem to break the habit either.

Touching your face is a problem because most of the time this involves touching the mucous membranes of our nose, mouth or eyes, which are more vulnerable to pathogens. Not touching your facial mucous membranes, an area known as the “T-zone,” and washing your hands are two of the most important steps you can take to help prevent infection.

The new coronavirus causing the current pandemic is classified as an “enveloped” virus; this means there’s an outer lipid (fatty) layer around the outside of the cell that makes it particularly easy to deactivate. Notice that the term isn’t “kill,” as viruses aren’t actually alive. They are “metabolically inert,” meaning they can’t replicate without a host; they must use the cells of a host (such as a human) to replicate.

The good news is that hand soap is very effective at disrupting enveloped viruses like coronavirus. The coronavirus has a membrane of oily lipid molecules, which is studded with proteins that help the virus infect cells. Soap molecules have a head that bonds to water and a tail that avoids it. Soap destroys the virus when the water-shunning tails of the soap molecules wedge themselves into the lipid membrane and pry it apart, deactivating the virus. Soap then traps dirt and the destroyed virus, which wash away in water.

It’s important to remember that antibacterial soap isn’t any more effective than regular soap. Remember how your doctor didn’t want to prescribe you antibiotics last time you had a cold? That’s because the common cold is caused by a virus – rhinovirus to be specific – and antibiotics are medicines that are only effective on bacteria. The same is true for antibacterial hand soaps; they are no more effective than regular soap at deactivating viruses because their added antibacterial chemicals are only effective on bacteria.

Now are you convinced you should wash your hands?

A note about how often to wash: I’ve been using the approach of every time I change activities or enter or leave a room. Open the fridge? Wash your hands. Restroom (of course, wash your hands!). Checked the mail? Wash your hands. Left the house for any reason? You know the drill. Right now, we need to be vigilant and change our behavior while we navigate these difficult new times.

Not many battles in this pandemic are going to be as easy and straightforward, but in the case of washing your hands, it’s something small but powerful we all can do to help protect ourselves and our loved ones.

 Go forth and be soapy.

-Jenna Arkin, ECOS Green Scientist & VP of Innovation