How does soap kill COVID-19?

Tired of washing your hands for 20 seconds each time? Fingers starting to prune or feel like sandpaper?Please don't stop.

The world is counting on you to help stop the spread of Covid-19, the deadly new disease caused by SARS-CoV-2, or severe acute respiratory syndrome Take heart that while you're scrubbing, you're also killing off a host of other nasty bacteria and potentially lethal viruses that have plagued humans for centuries -- including influenza and a number of different coronaviruses.

Coronaviruses aren't the only nasty parasites that succumb to a vigorous application of soap and water. Influenza -- which kills millions around the world each year -- and the human metapneumovirus, which causes a respiratory infection that can lead to pneumonia, also break down and die.

How did such a simple thing as soap and warm water ---- obtain such power over these parasites?

The answer lies in their "skin" and your scrubbing technique.

Just how soap accomplishes this feat is rather strange and fascinating science.

It's all about how soap molecules are formed -- each looks much like a tiny sperm, with a head and tail. The head bonds with water but the tail rejects it, preferring oil and fat.

Frantically trying to escape water, the tail of the soap is drawn to the fatty outer layer of the virus and begins to pry it open, much like we might use a crowbar to separate two pieces of wood.

Once the virus or bacteria splits open, it spills its guts into the soapy water and dies.

Water and scrubbing with your hands are important to this process because the combination creates more soap bubbles, which disrupt the chemical bonds that allow bacteria, viruses and other germs to stick to surfaces.

You want to scrub, build up bubbles and scrub some more, getting into every crack and crevice of your hands and fingers, including your fingernails, for 20 seconds, which is about as long as it takes to sing Happy Birthday twice. 

Now, when you rinse your hands, all the germs that have been hurt, trapped or killed by soap molecules are washed away.

Coffee Infused Soap

You often hear that the water you wash with should be warm, but why? After all, even hot water does not kill bacteria or viruses until you get to a temperature that would scald the skin..

To do that, you might need to sing "Happy Birthday" three times instead of two.

"Warm water with soap gets a much better lather, more bubbles," Wuest said. "It's an indication that the soap is ... trying to encapsulate the dirt and the bacteria and the viruses in them."