Why does soap work so well?
Mar 16, 2020, 12:42 PM | Updated: Mar 17, 2020, 11:12 am
Soap is basically magic. Getty Images
While the internet is lit up with stories about shortages of toilet paper and hand sanitizer, the CDC still says the best way to protect yourself from COVID-19 is plain, old-fashioned soap.
That’s because it wrecks havoc on germs.
The Science
Without getting too deep into the science jargon, soap has some unique properties that make it excellent for cleaning and stopping the spread of disease.
Dr. Pall Thordarson, a chemistry professor at the University of New South Wales, said the reason it’s so amazing has to do with its chemical makeup.
Thordarson said soap attacks and literally dissolves the COVID-19 virus weakest link: its fatty bilayer.
“The soap dissolves the fat membrane and the virus falls apart like a house of cards and ‘dies’, or rather, we should say it becomes inactive as viruses aren’t really alive,” he said. “Disinfectants, or liquids, wipes, gels and creams containing alcohol (and soap) have a similar effect but are not really quite as good as normal soap. Apart from the alcohol and soap, the ‘antibacterial agents’ in these products don’t affect the virus structure much at all.”
Disrupting that barrier is something that Thordarson says is vitally important to disrupting the spread of COVID-19.
Viruses
Viruses are nasty little nanoparticles that effectively “hijack” other cells and take over — much like a computer virus — and force healthy cells to start producing more copies of their own RNA (similar to DNA) that can then go on to infecting more cells.
“These new RNA and protein molecules, self-assemble with lipids (usually readily present in the cell) to form new copies of the virus. ” Thordarson said. “All those new viruses eventually overwhelm the cell and it dies/explodes releasing viruses which then go on to infect more cells.”
This becomes especially problematic when these viruses make their way into the lungs and airways because of how easily they can be spread when coughing or sneezing.
“When you cough, or especially when you sneeze, tiny droplets from the airways can fly up to 10 meters (30 ft)! The larger ones are thought to be main coronavirus carriers and they can go at least 2 m (7 ft).”
Virus lives on longer than you think
Even though those expelled droplets can dry out relatively quickly since viruses aren’t alive, Thordarson said they don’t “die” right away, but can continue to be active on favorable surfaces.
“The SARS-CoV-2 coronavirus is thought to stay active on favorable surfaces for hours, possibly a day. Moisture (“dissolves”), sunlight (UV light) and heat (molecular motions) all make the virus less stable,” he says.
The skin is one place that Thordarson says is most favorable for viruses.
“The skin is an ideal surface for a virus. It is “organic” and the proteins and fatty acids in the dead cells on the surface interact with the virus through both hydrogen bonds and the “fat-like” hydrophilic interactions,” he said. “So when you touch say a steel surface with a virus particle on it, it will stick to your skin and hence get transferred onto your hands. But you are not (yet) infected. If you touch your face though, the virus can get transferred from your hands and on to your face.”
With that being said, physical contact is something that can spread the virus effectively, and quickly.
“And now the virus is dangerously close to the airways and the mucus type membranes in and around your mouth and eyes. So the virus can get in…and voila! You are infected (that is, unless your immune system kills the virus).”
So what makes soap so special?
That, Thordarson says, comes down to chemistry.
Remember how viruses, like COVID-19, have a fatty layer surrounding them? Well, it’s that layer that the soap attacks.
“Soap contains fat-like substances known as amphiphiles, some structurally very similar to the lipids in the virus membrane. The soap molecules “compete” with the lipids in the virus membrane.”
Then, the soap effectively out-competes the virus and tears it apart.
“The soap also out-competes the interactions between the virus and the skin surface,” Thordarson said. “Soon the viruses get detached and fall apart like a house of cards due to the combined action of the soap and water. The virus is gone!”
Which soap is best?
According to Thordarson, soap is soap.
“Soaps, be it ye olde soap bar, a foamy hand-soap or something similar, have all been formulated to be dissolved and clean the dirt off your hands, without hurting even the most delicate skin of a baby,” he said. “For me the answer is obvious – soap! It works well and it won’t hurt your hands even if you are using it all the time. Now – the next question – which soap? I think you can guess my answer now – it probably does not matter!”
Is hand sanitizer bad?
In short: no. But it shouldn’t be the only thing you’re using.
“Take care of your hands,” Thordarson said. “Soaking them constantly in alcohol-based products is not good for them. It’s actually the same with soap. Yes, wash them frequently but don’t spend all day with your hands in soapy water. If your hands are hurting, something is wrong.”
“To summarise, just wash your hands with soap! Any soap – as long it is the real deal. Detergents are probably not good for your hands. Alcohol-based products do kill viruses and please use them whenever soap is not practical (e.g. when you are out and about).”
1/25 Part 1 – Why does soap work so well on the SARS-CoV-2, the coronavirus and indeed most viruses? Because it is a self-assembled nanoparticle in which the weakest link is the lipid (fatty) bilayer. A two part thread about soap, viruses and supramolecular chemistry #COVID19 pic.twitter.com/OCwqPjO5Ht
— Palli Thordarson (@PalliThordarson) March 8, 2020
How To Prevent the Spread of COVID-19 Coronavirus
COVID-19 coronavirus is transmitted from person to person. It is a virus that is similar to the common cold and the flu. So, to prevent it from spreading:
- Wash hands frequently and thoroughly, with soap and water, for at least 20 seconds.
- Don’t touch your face.
- Keep children and those with compromised immune systems away from someone who is coughing or sneezing (in this instance, at least six feet)
- If there is an outbreak near you, practice social distancing (stay at home, instead of going to the movies, sports events, or other activities.)
- Get a flu shot.
Local resources
State of Utah: https://coronavirus.utah.gov/
The Church of Jesus Christ of Latter-day Saints
Utah Coronavirus Information Line – 1-800-456-7707
National Resources
Centers for Disease Control and Prevention
Commonly asked questions, World Health Organization
