Covid-19 - Lesson 101

Updated: Jan 27

by Ayshwarya Ravichandran, Ph.D.

What is SARS-CoV-2?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that causes the disease, COronaVIrus Disease 19 (COVID-19). Viruses are minute parasite-like organisms, much smaller than bacteria, invisible to the naked eye and thrive and reproduce inside hosts like humans or animals.

Where did it come from?

SARS-CoV-2 is believed to have originated from bats as it is similar to a bat-coronavirus. However, it is highly likely that an intermediate host, such as pangolins or civet cats, was involved before it moved to humans since the viral protein that binds to human cells closely resembles those found in these higher mammals. The possible evolution mechanisms by which it could have transformed from its original form to the current version found in humans can be found here.

So far, the scientific community has found no concrete evidence supporting the conspiracy theories that suggest it was grown or modified in a lab.

How does it spread?

The virus primarily spreads from person to person via droplets that pass from an infected person to others primarily via nose, mouth and eyes. The infectious droplets can also contaminate surfaces for long periods of time and this is another possible way one is infected by the virus.

The chances of getting infected are higher if one shares a closed or air-conditioned space with an infected person since the droplets can remain longer in the air under such conditions due to poor air circulation. Personal protective gear is highly recommended for people working in such situations.

What are the symptoms associated with SARS-CoV-2?

This virus predominantly causes a lower respiratory illness, typically marked by cough and fever. About 3% of the patients are also known to have diarrhoea. Loss of sense of smell has also been noted as one of the typical symptoms of COVID-19. While about 80% of infected people show mild symptoms that do not require hospitalization, those with pre-existing conditions, such as cardiovascular diseases, hypertension, diabetes and immune disorders and elderly people (over 65 years of age) develop more severe symptoms. Of these 20%, about 15% may need supportive therapies in the hospital, while the remaining 5% require artificial ventilation and ICU care.

The incubation period (time between exposure and onset of symptoms) for the virus is between 2-14 days. However, an increasing number of cases show very late onset of the disease. For instance, the state of Kerala in India has reported many cases testing positive about 30 days after their return from other countries.

It is best to seek immediate medical attention if a person (especially those with a family history of the above-mentioned conditions) develops unusual symptoms.

Important note to parents: Do not ignore if your child exhibits abnormal lethargy or skin rashes/ discoloration or chest/ belly pain, in addition to the typical COVID-19 symptoms seen in adults. New reports are emerging that the disease causes a severe inflammatory syndrome that can affect multiple organs in children.

How can we protect ourselves?

  • Regular hand-washing, esp. after coming back from outside and/or touching surfaces outside the house like door handles, lift buttons etc.

  • Covering nose and mouth while coughing and sneezing.

  • Social distancing- maintain a minimum distance of 1 metre from anyone who doesn't live with you.

  • Avoid close contact with anyone showing symptoms of respiratory illness, such as coughing and sneezing.

  • Wear a mask while going to public places.

  • Maintain strict social distancing while meeting older people or people with pre-existing illnesses.

  • Avoid visits to crowded places unless absolutely necessary.

Are there any treatments available for treating SARS-CoV-2?

Although certain drugs or combinations were thought to be effective against COVID-19 earlier, no solid evidence is available till date. Antibiotics work only against bacteria and not viruses and antibiotics should not be taken preemptively against viruses. Only a limited number of antiviral drugs are available in the market.

Nevertheless, scientists and medics are working tirelessly across the world to find a solution to this nightmare. Globally, there are over 200 programs involved in developing treatment strategies against COVID-19, including vaccines against different components of the virus, antivirals and their combinations. Some of these are listed here. Hence we can hope that at least one of them, if not a few, will prove fruitful in bringing this crisis to a halt.

Related pages and videos to learn more about COVID19

India Alliance WellcomeDBT Resource Hub -

Indian Research Institutes consortium hosted site -

Dr. V. Ramasubramaniam, Senior Consultant, Infectious Disease, Apollo Hospitals, Chennai

The blog was written based on information available as of 21/05/2020.

Note: Please consult a medical professional or a trained nutritionist regarding specifics of your health and symptoms or before changing your diet or trying something new.

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#covid19 #sars-cov2 #symptoms


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