The story so far: Ever since the novel coronavirus (SARS-CoV-2) outbreak began in China in end-December 2019, various measures have been mentioned to reduce the risk of infection. Guidelines by the World Health Organization specify that one of the ways to reduce the risk of infection is by regularly and thoroughly cleaning one’s hands with an alcohol-based hand rub or washing them with soap and water. Regular washing becomes important as the virus tends to be viable from hours to more than a day on different surfaces that are regularly touched with hands.
How does washing with soap help get rid of the coronavirus?
The grime on our hands contains innumerable viruses and bacteria. Washing with water without using soap helps reduce the amount of microbes but does not remove most of the virus and bacteria completely. Using soap, therefore, becomes far more effective in removing microbes.
Viruses such as coronavirus, influenza-causing viruses, Ebola, Zika have their genetic material encased in a layer of fat called the lipid envelop. Soap molecules are pin-shaped with a head that is water-loving (hydrophilic) and a tail that is oil-loving (oleophilic). Being oleophilic, the tail portion of the molecule tends to have an affinity for and ‘competes’ with the lipids in the virus envelope. Since the chemical bonds holding the virus together are not very strong, the long oleophilic tail gets inserted into the envelope and tends to have a ‘crowbar’ effect that breaks the lipid envelope of the virus. The tail also competes with the bond that binds the RNA and the lipid envelop thus dissolving the virus into its components which are then removed by water.
Do all viruses have the lipid layer?
No, certain viruses do not have the lipid envelop and are called the non-enveloped viruses. Rotavirus which causes severe diarrhoea, poliovirus, adenovirus that cause pneumonia and even human papillomavirus (HPV) do not contain the lipid envelop.
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The oil-loving tail of the soap molecule also disrupts the bond that binds dirt and non-enveloped viruses to the hand. The dirt and viruses are surrounded by several tails making them remain as suspended particles. Rinsing with water washes away the suspended particles leading to clean hands.
How do alcohol-based hand sanitisers help get rid of coronavirus?
Like soap, the alcohol present in hand sanitisers dissolve the lipid envelop, thus inactivating the virus. In addition, the alcohol also tends to change the shape or denature the mushroom-shaped protein structures that stick out of the lipid envelop. The mushroom-shaped protein structures help the virus to bind to special structures found on human cells and enter the cells. To be effective, the sanitisers should contain at least 60% alcohol.
Unlike soap lather, the alcohol does not come in contact with all parts of the hand. So care needs to be taken to use sufficient amount of sanitiser to increase the coverage . Unlike water, alcohol run does not remove the dead viruses from the hand. While a sanitiser can quickly reduce the number of microbes, it does not get rid of all types of germs, and is “not as effective when hands are visibly dirty or greasy”.
Should healthy people who are not taking care of COVID-19 patients use a mask?
Medical masks help prevent the spread of coronavirus infection. If worn properly, masks may be effective in preventing transmission of coronavirus. An article published in the Journal of the American Medical Association (JAMA) says there is no evidence to suggest that masks worn by healthy individuals can help prevent infection.
But a 2010 study says: “Mask wearing was associated with reduced secondary transmission and should be encouraged during outbreak situations.”
Even the World Health Organization (WHO) says wearing a medical mask is “one of the prevention measures to limit spread of certain respiratory diseases, including novel coronavirus (SARS-CoV-2), in affected areas”.
Transmission through droplets from coughing and sneezing is one of the major routes of virus spread. When worn correctly, a mask can reduce the risk of inhaling droplets containing the virus.
With many studies showing that people infected with novel coronavirus transmit the virus even before symptoms show up, it may be prudent to wear a mask especially when the virus is spreading in the community.
In a country like India, maintaining at least one metre distance can be a challenge, especially when there is no way of knowing who is infected till such time the person starts showing visible symptoms.
What other precautions should be taken when a mask is used?
WHO cautions that using a mask alone will be insufficient to provide an “adequate level of protection”. It should be combined with hand hygiene to prevent human-to-human transmission. Wearing medical masks can give a person a “false sense of security that can lead to neglecting other essential measures such as hand hygiene practices”. So if an individual decides to wear a mask, care must be taken to regularly wash hands with soap or alcohol rub, and avoid touching the face with hands.
Incorrect mask wearing might otherwise reduce the effectiveness in cutting the risk of transmission. It should be discarded once it gets wet or dirty, and care should be taken to safely dispose of used masks. The same mask should not used for more than a couple of hours.