Covid-19: Knowing the Instruments of Household Hygiene

A VIRUS, often measuring one nanometre in size, is invisible under a common light microscope, to say nothing of the naked eye.

Each virus is unique but relies on living cells to host its reproduction. This is achieved using a lock-and-key mechanism, e.g. the virus functions as a “key” that unpicks the “lock” that is the surface of the host cell. Upon gaining entry, the virus either takes over and makes use of the host cell’s resources to replicate, or it injects its genetic materials (known as provirus) into the host genome and deceives the host cell into replicating the virus.

Once enough copies have been reproduced, the virus enters the blood circulatory system to infect other host cells with the same unlocking mechanism. At some point, the host organism’s immune response kicks in and starts to fight the virus.

The coronavirus is a large family of viruses found mostly in animals. It is liable to cross-species transmission, travelling from animals to infect humans through mutation. Covid-19, along with the Middle East Respiratory Syndrome (MERS) and the Severe Acute Respiratory Syndrome (SARS), is one of the most notorious illnesses to have infected humans in recent times. Signs of infection range from mild, flu-like symptoms to severe respiratory distress and even death.

While the hunt goes on for the “best” and “most effective” hand sanitisers, the humble soap has been largely neglected.

Covid-19 is caused by the SARS-CoV2 virus, a sister clade to the SARs-CoV strain that resulted in the SARS outbreak back in 2003 (Nature Microbiology, 2020). Though not as deadly, Covid-19 is more infectious (measured in R0) than the seasonal flu. Its rapid spread is exacerbated by a long incubation period of up to 14 days, during which asymptomatic carriers may unknowingly infect others. Although current evidence suggests that Covid-19 is primarily transmitted between people via water droplets and direct contact, the World Health Organization (WHO) also advises that airborne precautions be taken, especially in settings where aerosol generating procedures and support treatment for the care of Covid-19 patients are performed (WHO, 2020).

Additionally, the virus can be transmitted in all climes and environs. Hence, proper sanitisation and personal hygiene is of utmost importance.

The Hand Sanitiser

Demand for hand sanitisers soared during the pandemic. Hand sanitisers contain ethyl alcohol (ethanol) or isopropyl alcohol, with high alcohol content (typically 60-80%) and water. This formula effectively kills viruses and bacteria through protein denaturation within 10 seconds.

As alcohol is a highly volatile solution, it can vaporise and become flammable upon contact with any spark, flame or with a sudden increase in temperature. Interestingly, some have taken to applying it the way they would hand moisturisers. Glycerine, an added ingredient in hand sanitisers, functions as a humectant which helps to absorb water and retain skin moisture in order to counteract dehydration caused by the high alcohol content, but it cannot be used in place of actual moisturisers and may still cause dryness.

Motivated by the disinfecting properties of alcohol, some people have also started using stronger variants as cleaning detergent to wipe down counter tops and to mop floors with. In principle, this practice makes sense; however, solutions with high alcohol content are naturally evaporative. What is concerning is that the fumes from the alcohol, especially in an unventilated and confined space, is highly flammable, and can expand and explode with just a tiny spark or any source of ignition, like the turning on of a stove. It would instead be less hazardous to use cleaning agents that are advertised as household disinfectants.

Another concern within the scientific community is the practice of drinking large quantities of alcohol as a way of sterilising oneself against the Covid-19 virus. As mentioned, the alcohol concentration required to kill viruses and bacteria ranges from 60% to 80%; for human consumption, however, this high concentration can prove fatal.

To compare, the alcohol content found in beers is 4% or less, while in whiskey, this hovers around 40% - both are significantly below the required dosage needed for the purpose of decontamination. Drinking alcohol to prevent contracting Covid-19 is a pointless effort, as the primary infection target are the lungs, which are separated from the digestive track where consumed alcohol would pass through.

The Humble Soap

While the hunt goes on for the “best” and “most effective” hand sanitisers, the humble soap has been largely neglected. In reality, the soap, which has been around since the time of Babylon, is just as, if not more, potent than hand sanitisers in combating the Covid-19 virus. After all, it has protected humanity from diseases for centuries.

Soap is made up of molecules which consist of hydrophilic (water-loving) heads and hydrophobic (water-hating) tails. When one lathers soap onto wet hands or the body, the molecules that come into contact with water form what are known as micelles.

Micelles are soap molecules that are gathered in such a way that the hydrophobic tail is turned inwards away from water, while the hydrophilic head is turned outwards. When micelles come in contact with fatty materials, such as the protective lipid layer that surrounds viruses, the hydrophobic part of micelles dissolves the fatty substances, thereby destroying the virus. Any remnants of the virus can then be completely washed off the skin with water.

Detergents and Bleaches

On its website, the US’ Centers for Disease Control and Prevention details instructions for the cleaning and disinfection of households and commonly touched areas such as doorknobs, tables, switches, toilets and electronics (CDC, 2020). The public is advised to clean the surfaces of these areas with appropriate disinfectants in a safe and effectual manner; for example, ensuring proper ventilation and wearing gloves while cleaning. Detergent or soap and water can be used to clean surfaces. Subsequently, diluted household bleach can be used to disinfect and kill any remaining germs, and to ensure that the disinfectant is given enough contact time on the surfaces to work its magic.

The combined use of both detergent and bleach is generally sufficient for the purpose of sanitisation. While soap works in breaking down the protective lipid layer of viruses, the sodium hypochlorite in bleach destroys the protein and genetic material [usually ribonucleic acid (RNA)] responsible for the replication of viruses in the infected host. Hence, destroying the RNA in the virus invariably stops its spread.


• Nature Microbiology. 2020. "Coronaviridae Study Group of the international committee on Taxonomy of, v., The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-ncov and naming it SARS- CoV-2." Nature Microbiology. vol. 5 issue 4, p536- 544.

• WHO. 2020. "Q&A on coronaviruses (COVID-19)." WHO. 17 April. https:// coronaviruses.

• CDC. 2020. "Cleaning and Disinfection for Households." CDC. 27 May. https:// prevent-getting-sick/cleaning-disinfection. html?cDc_AA_ref val=https%3A%2F%2Fwww. ncov%2Fprepare%2Fcleaning-disinfection.html.

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