How soap kills the coronavirus

Faced with empty shelves of hand sanitiser in the supermarket? Relax. Soap will do a better job of dissolving Covid-19.

Any soap will do, liquid soap, bar soap, body wash or even shampoo. If you’re really short, washing up liquid or laundry detergent will work, though if you want to avoid dry hands, you might not want to make this your go-to option. Remember, we're in this for the long haul, so you'll want to take good care of your hands.

How soap breaks down viruses

Soapy water contains amphiphiles, a chemical compound made up of hydrophilic (water-loving) and hydrophobic (water-hating) properties. With a bit of agitation, these amphiphiles will break down the fatty layer, “the coat ”, that protects the  virus.

Soap breaks it down and water rinses it clean away. If you want to read more about the science behind the theory, catch up with Professor Palli. 

Viruses can be active outside the body for hours, even days. Disinfectants, liquids, wipes, gels and creams containing alcohol are all useful at getting rid of them – but they are not quite as good as normal soap.

Professor Palli Thordarson, School of Chemistry UNSW

Why soap is better than hand sanitiser for shifting germs

Hand sanitiser uses alcohol to kill the virus which means you have to soak your hands in ethanol for a brief moment to kill the virus.  Soap and water is more thorough; it kills the germs and then physically dislodges them, rinsing them down the drain.

If you use a pepper and oil analogy, with the pepper representing the virus:- 

Dip a finger into a bowl or pepper and oil, nothing happens. 

Now dip a finger covered in hand sanitiser into the bowl, the pepper disperses. 

Here's the gold standard approach - dip a finger covered in soap into a bowl, the pepper disperses much further.  (Try it and see, we did) 

So, in short, wash with soap when possible, and hand sanitiser if out and about and away from a sink.

The Handwashing Guide 

Using soap alone won’t be enough, for maximum effect you need to follow the golden rules. 

The 20 seconds rule

This gives you the time to lather up and break down the virus. Follow the NHS guidelines for step by step instructions, but the important thing to remember that quality and quantity counts. In that 20 seconds, you have time to wash all parts of your hands - palms, backs, fingers, thumbs and wrists.

Be vigorous

The virus likes to stick to the cracks and ridges of the hands, which is why a really good hand wash using lots of friction will break down the virus, wherever it's hiding.

Rinse well

Rinse the germs away with clean water. Not too hot, or you’ll end up with dry hands over time.

Dry thoroughly

An extra rub with a clean cloth towel or fresh paper towel will dislodge any remaining germs.

If you want to make life easy on yourself, keep your nails short so there is nowhere for germs to hide, otherwise use a scrubbing brush each time.

Finally, look after one another

Teach your children, grandchildren and all the people you love how to wash their hands, but keep it relaxed. Washing our hands is just something we do to keep ourselves and others healthy. These are good habits for life.