A History of Violence—How Soap Attacks a Coronavirus

The SARS-CoV-2 virus, the cause of COVID-19, taking over the Earth like a zombie apocalypse, making us hide in our houses, is actually quite a bit easier to destroy than a zombie. Simple soap will tear it apart. You can use a host of other chemicals, too, many that you have lying around, like alcohol and bleach, but for the special way that soap works, there is no reason to look any further than your soap dispenser.

The SARS-CoV-2 virus, as contagious as it is, is not a hardy virus. Outside the body, in the wild, the SARS-CoV-2 is a wuss. It won’t survive for long outside a warm, moist environment, like the host cells in the human respiratory system, for which it has a special affinity. Unlike the other class of viruses called “naked” viruses, essentially dry particles with hard protein shells, coronaviruses belong to the class of enveloped viruses, which are covered by a bilipid (lipid =fat) layer that will suffer from desiccation. They are also extremely vulnerable to chemicals, such as surfactants (soap and detergents).

When a COVID-19 victim coughs, sneezes, defecates and maybe even exhales, the virus’ clock starts ticking very loudly. It simply has to get back inside someone quickly or it will perish. The SARS-CoV-2 virus lasts only  four hours in droplet form, one day on cardboard (think the boxes being delivered to your door), two days on stainless steel, and three days on plastic surfaces, according to a study published in the New England Journal of Medicine.

The best outcome, from the point of view of a virion, is for it to be inhaled by another human. The warmth, moisture and pH of the human breathing passage is the ideal breeding ground for the SARS-CoV-2. Once in a body, it can go back to work, doing what it does best—breaking into cells, hijacking the cell machinery for its purposes, and replicating itself by the tens of thousands with each hijacked cell. The immunological reaction it causes is inadvertent and unfortunate, an overreaction by the body that results in a fever. The debris accumulating in the lungs from the damage to the pulmonary alveolus is like painting over a wall, explains Dr. Sanjay Mukhopathguy, a lung pathologist at the Cleveland Clinic. The damage to capillaries also causes them to leak plasma proteins that add to the wall’s thickness.

Of course, once the host organism is terminally compromised, the lungs covered with fluid, effectively drowning the victim, the virion’s only hope is to be expelled.

But if it is not lucky enough to be breathed in—the most ideal outcome for the SARS-CoV-2 virion—there are secondary ways that it can get inside another human. For example, the human touches a surface that a sneeze or cough droplet has landed on, which then introduces the virion to the nose or mouth. You might be touching your face as you read this—and that is exactly what the virion needs you to do.

Naked and Not Afraid

Viruses can be broken down into two types: naked and enveloped.

Naked viruses, the simplest form of virus, are little more than a genome inside a protein shell called the capsid. Imagine a ruggedized, armored speck of dust. In its primitive state, armored against the world, it is protected against all manner of threat, such as solvents, acids (like stomach acids), changes in pH, surfactants, temperature and humidity fluctuation, or lack of moisture—even the rigors of time. Naked viruses can exist in their dormant state for a long time, perhaps forever. An ancient virus from 30,000 years ago was found in Siberia’s permafrost. Thawed, it was able to infect again.

Other viruses have the same genome and capsid but add an envelope made mostly of lipid. Lipids are best known by their common name: fats. When lipids are liquid, they are called oils. Your body fat is a lipid. So is olive oil.

An enveloped virus, its envelope consisting of a dual layer of lipid molecules with a few proteins stuck in it, is considered a more evolved type of virus. The envelope is said to cloak the virus from antibodies. The lipids and proteins in the envelope may be considered similar to the host’s cells, which are also composed of fats and proteins. This allows the enveloped virus to replicate undisturbed in the host. But the envelope also contributes to its vulnerability.

As anyone who has ever washed a dish is probably aware, soap and detergents dissolve fat and oils.

Surfactants, which include both soap and detergent, break down the lipid layer. Stripped of the envelope, the virus is now naked and exposed … and at the mercy of antibodies. In addition, its ability to replicate has been severely compromised. The protein spikes that stuck through the lipid bilayer, which are necessary to inject the viral genome into the host cell, have been uprooted and rendered useless.

How Soap Violently Attacks the Coronavirus

Surfactants work by creating polarized molecules, with one end that loves water (hydrophilic) and the other that loves fat (hydrophobic). In water, the molecules float around in water. If they encounter each other, they assemble in clusters, called micelles, with heads together and tails to the outside.

A coronavirus is no more than a “nano-sized grease ball,” said Palli Thordarson, PhD, and professor of chemistry at the University of Sydney, whose multipart Twitter treatise may have earned him the title of Dr. Soap. The fat-loving, water-hating ends of the soap molecule bury themselves into the bilipid layer of the coronavirus, prying it apart.

It doesn’t take much force to pry the bilipid layer apart. The globs of lipids and protein in the virus’ outer membrane are held together weakly with hydrogen bonding and Van der Waals forces, explains Thordarson, unlike the stronger covalent bonds that bind other materials, from diamonds to skin.

The soap molecules are not only weakening the outer membrane of the virus, they are also reforming into micelles, encircling the lipid molecules like wolves, prying chunks off the bilipid layer, perforating what was once a waterproof cover and exposing the virus’ innards. The coronavirus membrane is perforated, the capsid is flooded with water and exposed to antibodies. The protein spikes that stuck through the lipid bilayer—necessary for the virus to inject its genome into a host cell in order to replicate -- are uprooted and rendered useless.

With enough soap and time the viral envelope will have been broken up into pieces. Micelles wrap up the parts of the demolished virus and are washed away.

The whole attack takes 20 seconds.

It is the active fat-seeking property of the soap molecule that makes it so effective against the coronavirus and other enveloped viruses. Surfactants, like soap, are less effective against naked viruses, as well as hard cases like bacteria that can cause meningitis, pneumonia and diarrhea, which have shells that are made of proteins and sugars (not fat).

The explanation of how soap works to destroy the COVID-19 virus has propelled Thordarson into something of a celebrity scientist, resulting in radio, TV and magazine interviews. Thordarson went from a bachelors in chemistry in his native Iceland to a PhD at Australia’s University of Sydney.

The Bloody History of Soap

Legend has it that the fat from a burning animal sacrifice made a lather in a river that was able to clean skin and clothes. The Romans made a record of soap 2,300 years ago, perhaps getting it from the Celts’ saipo, a product of animal fat and wood ashes. In the Middle Ages, chemistry introduced lye into the soap making process. A modern soap is a combination of fat (triglyceride) and lye (sodium hydroxide). More chemistry created detergent, which substitutes chemicals for fat. During World War I, the Germans, who needed fat for other purposes, made a synthetic detergent. Both soap and detergent fall into a class of products called surfactants.

Ignaz Semmelweis, a Hungarian doctor in the 1840s, now known as the father of handwashing, found that doctors who washed their hands had far fewer patients die from childbirth. Germs hadn’t yet been discovered. It was a time when doctors visited one patient after another wearing aprons encrusted with blood, like badges of honor. They would invite the great unwashed (the general public) to watch their surgeries.[i] The hygiene Semmelweis proposed was met with ridicule and led to his ostracism. The good doctor went mad.  A beating by sanitarium guards caused wounds that became infected. Semmelweis died of sepsis, an infection in the bloodstream—the very affliction he had tried to reduce by encouraging the practice of handwashing.

All Washed Up?

The best way to stop the contact spread of COVID-19 appears to be good, old-fashioned soap—provided you do it often and long enough. A 20-second wash is adequate and provides enough time for the soap molecules to destroy the lipid layer of the SARS-CoV-2 virus. A 17-year-old created Wash Your Lyrics, an online program that fashions a 20-second version of the song of your choice. But the best advice comes from Dr. Bonnie Henry, the top health official from British Columbia, who said, “Wash your hands like you’ve been chopping jalapeños and you need to change your contacts.”