Classification of Coronavirus Varients

Rewinding back to the dawn of 2020 when the world thought it is the start of a new decade and were really looking forward to it, no one would have thought that a small RNA virus would turn the table. On December 2019 at Wuhan city, in China few people were diagnosed with pneumonia. The cause being unknown the situation was reported to WHO. Later when research was conducted it was found that the cause of illness was the novel “Coronavirus”.

Origin

The name coronavirus has evolved from Greek word korṓnē, meaning ‘wreath’. The earliest reports of this virus occurred back in 1920s, when acute respiratory infection of chickens emerged in North America. From then onwards continuous studies and researches have been made and in 1971 the name ‘Coronavirus’ was accepted as the genus name by International Committee for the Nomenclature of Viruses. Most of the human coronaviruses have their origin in avian rodents such as bats.

Definition and Structure

Coronavirus belongs to the group of RNA Viruses that have genomes made of ribonucleic acid (RNA), which cause respiratory tract infections such as pneumonia in humans. 

Coming to the structure of the virus, from the above illustration it can be seen that these viruses are spherical shaped particles with spike type projections on their surface. As compared to the above figure, the Grey surface is the outermost membrane of the virus particle made of lipids. There are two such layers. Thus, it also known as the lipid bilayer envelope. The Red spikes projections are called spike proteins(S) composed of glycoproteins whereas the Yellow and Orange projections are envelope(E) and membrane(M) proteins respectively.

 

Classification

Coronaviruses are classified into four categories:

• Alphacoronavirus.
• Betacoronavirus.
• Gammacoronavirus.
• Deltacoronavirus.

α-CoV and β-CoV infect mammals while the other two are harmful for birds.

The one that affects Humans!

Coming to the Coronavirus species there are 45 species known till date (2020). 7 of them infect humans. These 7 can be further divided into 2 groups based on the ability to control them.

The one which have been contended:

• Human Coronavirus OC43 (HCoV-OC43), β-CoV.
• Human Coronavirus HKU1 (HCoV-HKU1), β-CoV.
• Human Coronavirus 229E (HCov-229E), α-CoV.
• Human Coronavirus NL63 (HCoV-NL63), α-CoV.

The above viruses produce symptoms of Common Cold mostly active during winter season. The severity of these viruses is low.

The one which are hazardous:

• Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), β-CoV (identified in 2003).
• Middle East Respiratory Syndrome related Coronavirus (MERS-CoV), β-CoV (identified in 2012).
• Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), β-CoV (identified in 2019).

Electron microscope image of SARS virion	Electron microscope image of MERS viron

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

SARS-CoV-2 also known as COVID-19 was first identified in China and from then onwards it has spread to every corner of the world at a rapid pace affecting and taking millions of peoples’ lives. It is the first time that it was declared as the global pandemic or a public health emergency of international concern, the highest level of alarm under international law (by WHO) since the Spanish flu of 1918. The SARS-CoV-2 has 70% genetic similarity to SARS-CoV and has 96% similarity of bat coronavirus.

Transmission

The SARS-CoV-2 is a communicable/contagious disease. This virus enters the human body by an aerosol (suspension of fine particles or liquid droplets in atmosphere) path. It targets the epithelial cells of the respiratory tract (as its host) and binds to the Angiotensin-Converting Enzyme 2 (ACE 2) receptors. Thus, making the person contagious.

Symptoms and Testing

Following is the common list of symptoms of people infected with COVID 19 (as per CDC):

• Cough
• Shortness of breath or difficulty breathing
• Fatigue
• Muscle or body aches
• Headache
• New loss of taste or smell
• Sore throat
• Congestion or runny nose
• Nausea or vomiting.

People who have above symptoms are tested and the most common tests include the RT-PCR (Reverse Transcription Polymerase Chain Reaction) test, RAT (Rapid Antigen Test) and CT (Computerised Tomography) scans (to check the virus spread, usually CT scans are not recommended).

Variants of SARS-CoV-2

While spreading from one person to another the virus copies itself and during this process some changes take place, termed as mutation. After mutation the virus is no longer similar to its previous version. This virus is titled as a variant of the reference virus.

Coming to the COVID-19 variants, WHO has classified them into two categories:

• Variants of Interests (VOI).
• Variants of Concern (VOC).

The statements issued by WHO regarding the definitions of VOI and VOC are as follows:

Variant of Interests

A SARS-CoV-2 isolate is a Variant of Interest (VOI) if it is phenotypically (changes in the epidemiology, antigenicity, or virulence or changes that have or potentially have a negative impact on available diagnostics, vaccines, therapeutics or public health and social measures) changed compared to a reference isolate or has a genome with mutations that lead to amino acid changes associated with established or suspected phenotypic implications; AND has been identified to cause community transmission /multiple COVID-19 cases/clusters, or has been detected in multiple countries.

Variant of Concern

A VOI is a Variant of Concern if, through a comparative assessment, it has been demonstrated to be associated with;

• Increase in transmissibility or detrimental change in COVID-19 epidemiology;
• Increase in virulence or change in clinical disease presentation; or
• Decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics.

List of VOC

List of VOI

How can the impact be reduced?

• Vaccination Drives must be held in large amount.
• Implications of Lockdowns (Already being implemented).
• Awareness among people to follow the Covid-19 protocols. The population of India is more than 1.2 billion, no matter how many measures are taken by govt. safety can only be ensured when every individual of the nation follows the norms set by the authorities. 
• Swift supply of medical equipment and setting up more no. of temporary COVID-19 care facilities.
• Taking the help of military to set up field hospitals.

Treatment and Vaccination

There is no general treatment for the SARS-CoV-2 but most people who have tested positive are prescribed to take Anti-Biotics and Multivitamins as medication and are suggested to eat protein diet. All these steps though may not prevent us from the virus directly but indirectly they boost our immunity. People with strong immunity have less severity against the virus.

Convalescent Plasma Therapy is also another way of post Covid-19 treatment but it has not been found much effective and is likely to be dropped from Clinical Management Guidelines on Covid-19. 

When the condition of patient is critical steroids like dexamethasone are provided to prevent mortality. This drug is only provided when there is inflammation that is preventing oxygen from flowing to the lung and it is given to reduce the inflammation.

Currently vaccination is considered as the most effective way to prevent Covid-19. The Vaccination programme in India began on 16 January 2021. Around 10% of the population received its first dose whereas 3% of the population has received both doses by the end of april. In India the vaccines approved under emergency use are listed below:

Name	Company	Efficiency	No. of Doses
Covishield	Serum Institute of India	63%	2
Covaxin	Bharat Biotech	81%	2
Sputnik-V (Yet to be launched)	Gamaleya Research Institute of Epidemiology and Microbiology	91%	2

Prevention of COVID-19

This Virus cannot be treated but can surely be prevented! Some of the preventive measures needed to be taken are listed below:

• Wear Masks PROPERLY. While wearing a mask one should keep in mind the mask should cover all nose, mouth and chin.
• Wash hands after reaching home. Avoid touching face all the time.
• Maintain social distancing (At least 6 ft.)
•  Don’t come out of the house unless necessary.
• Workout daily and eat healthy food. It helps in improving the immunity. Don’t stress yourself, stay strong and stay motivated.
• Whenever available get vaccinated as soon as possible.

STAY HOME, STAY SAFE & 

GET VACCINATED!

References:

• Wikipedia
• WHO (World Health Organisation)
• CDC (Centre of Disease Control and Prevention)
• The Hindu
• The Indian Express
• The Times of India
• NDTV

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