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Infectious Diseases

Updated 17 March 2020

"Simply wash your hands," experts say. Why are soap and water so effective in protecting against the coronavirus?

“Simply wash your hands,” experts say. But what is the science behind this simple protective measure?

As people raid the shelves for protective masks, toilet paper and hand sanitiser, experts are punting a very simple piece of advice – regularly and thoroughly wash your hands with soap and water.

Are we following your advice? And what is the science behind washing your hands?

What exactly is soap?

Soap has been used for many centuries and is essentially a mixture of fat or oil, water and an alkali or a salt base.

These ingredients go through a chemical process called saponification, which results in soap.

How does soap work?

Here’s a shocker – soap doesn’t actually kill germs on our hands – it simply removes them. As our hands get sticky, dirty or sweaty during the course of the day, nasty things on the surfaces of desks or our phones, bathrooms, or from other people’s hands stick to our hands and can enter our bodies when we touch our eyes, noses or mouths.

But when we wash our hands under running water, it removes these germs clinging to the surface. The soap molecules bind with both water and oil and allow both to be washed off our hands.

In the case of the new coronavirus, the virus spreads through liquid droplets expelled into the air, through coughing or sneezing. These droplets stick to people's hands when they cover their mouths.

For people who are infected with the virus, leaving hands unwashed results in the droplets remaining on your hands – and being transferred to the objects and people you touch.

But this applies to people who are not infected too – thoroughly washing your hands could potentially stop you from contracting the virus, if you have potentially come into contact with somebody who is infected, or objects that have been contaminated by somebody who has been infected.

The risk of you the touching your face with contaminated hands would be high, and the virus could enter your body through your nose, mouth, or eyes.

A thorough hand washing will remove these droplets – and the virus – from your hands, and curb the spread.

What about hand sanitiser?

While the World Health Organization (WHO) suggests soap and water as your best protective measure, hand sanitiser is a good backup – but only if the alcohol content is 60% or higher.

Hand sanitiser, unlike soap, doesn’t wash away germs. It kills bacteria and germs on the surface by breaking down their protective membranes. Some viruses, such as the norovirus which causes stomach ailments, are coated by a protective cap that isn’t always killed off by hand sanitiser.

There is no harm in carrying hand sanitiser if you aren't close to a tap and soap, but make sure that the alcohol content is high enough.

How (and when) to wash your hands

The WHO recommends washing your hands when they are visibly dirty or soiled with blood or bodily fluids, or after using the bathroom.

You should wash your hands even more frequently when you are taking care of the vulnerable and ill.

The WHO suggest that you should apply a palmful of soap or handwashing liquid to a cupped hand, and rub hands palm to palm, while interlacing your fingers to cover every surface of your hands. This should be done for at least 20 seconds. Rinse and dry your hands properly.

READ | Coronavirus in SA: All the confirmed cases

READ | Hand washing works whether water's hot or cold

SEE | Clean hands can prevent flu

READ | Will hand sanitiser clean my hands properly?

Image credit: iStock