Updated: March 17, 2020 4:38:08 pm
Amid the COVID-19 outbreak, India’s Health Ministry, organisations such as the World Health Organisation (WHO), the US Centres for Disease Control and Prevention (CDC), and UNICEF, as well as individual doctors across the world have advised people to wash their hands thoroughly — for at least 20 seconds — with soap, preferably using warm water.
It is important that you keep your hands clean at all times to prevent diseases, and especially during any viral influenza-like outbreak.
You can get germs on your hands by touching anything that may have got germs on it after an infected person coughed or sneezed on it, or after it came into contact with another object that was contaminated.
Once you get these germs on to your hands, you can get sick by touching your face, mouth, or nose (which most people do involuntarily every few minutes), and can pass them on to others — either through direct touch such as shaking hands with them, or via surfaces such as tabletops or door handles, etc.
This chain of transmission can be broken if you wash your hands of the germs.
The SARS-CoV-2 virus is transmitted through droplets, which are released when an infected individual coughs or sneezes. (It can’t just fly across and infect you.)
If a healthy person were to come in contact with these droplets by, for example, touching a contaminated surface (such as a handrail in a mall escalator or a straphanger in a bus, train, or Metro) and then touches their mouth, eyes or nose, they could catch the infection.
The droplets from coughs and sneezes can fly fairly far (upto 20 feet in some cases), and while the droplets may dry out after some time, the virus remains active for longer.
How does soap work to destroy the virus?
Soap is effective essentially because it destroys the lipid bilayer of the virus, causing it to collapse and ‘die’.
In a detailed thread posted on Twitter, Prof Pall Thordarson of the University of New South Wales in Australia, an expert of supramolecular chemistry and the assembly of nanoparticles, said soap works so well on most viruses including SARS-CoV-2 “because it (the virus) is a self-assembled nanoparticle in which the weakest link is the lipid (fatty) bilayer”.
The soap, he said, “dissolves the fat membrane and the virus falls apart like a house of cards”.
Most viruses are made up of RNA, proteins, and lipids, which “self-assemble” to form the organism. The RNA, Prof Thordarson said, is the virus’s genetic material, very similar to DNA. The proteins are the key building block in the virus structure, and help it break into the target cell and assist with replication. The lipids “form a coat around the virus, both for protection and to assist with its spread and cellular invasion”.
There are no strong “covalent” bonds holding these units together; rather, the viral self-assembly is based on weak “non-covalent” interactions between the proteins, RNA and lipids, Prof Thordarson said. Washing your hands with just water may not be enough; this is because water ‘only’ competes with the strong ‘glue-like’ interactions between the skin and virus via hydrogen bonds — and the virus is quite sticky and may not budge, he said.
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“Soapy water”, though, “is totally different. Soap contains fat-like substances knowns as amphiphiles, some structurally very similar to the lipids in the virus membrane. The soap molecules ‘compete’ with the lipids in the virus membrane”, as well as with “a lot other non-covalent bonds that help the proteins, RNA and the lipids to stick together”.
Thus, the soap, Prof Thordarson wrote, “is effectively ‘dissolving’ the glue that holds the virus together”. The soap also “outcompetes the interactions between the virus and the skin surface”, and the virus gets detached due to the combined action of the soap and water, he said.
What about hand sanitisers?
They are helpful if soap and water aren’t readily available — they are, in fact, substitutes that appear fancier while being actually somewhat less effective.
Prof Thordarson wrote: “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. Consequently, many antibacterial products are basically just an expensive version of soap in terms of how they act on viruses. Soap is the best but alcohol wipes are good when soap is not practical or handy (e.g. office receptions).”
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