Different Variants of COVID-19/SARS-CoV-2 virus

Table of Contents

Introduction of Corona Virus:

Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases.
Corona virus is the most common type of virus especially present in animals.
A coronavirus identified in 2019, SARS-CoV-2, has caused a pandemic of respiratory illness, called COVID-19/Corona Virus Disease-19.
This newly identified (at the end of 2019 in China) corona virus named as SARS-CoV-2 was the most infectious type of virus which quickly spread around the world.

What is Novel Corona Virus?

A novel coronavirus (nCoV) is a new strain that was not previously identified in humans.
This novel/new virus was subsequently named as “COVID-19 virus” by World Health Organization (WHO).
The disease caused by it was called as Corona Virus Disease-19 or COVID-19.

What is COVID-19?

Corona Virus Disease-19 (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus.
This disease can trigger the respiratory tract infection and affect upper as well as lower respiratory tract.
Corona Virus Disease (COVID-19) results mild to moderate respiratory illness and can recover without requiring special treatment. However, some will become seriously ill and require medical attention
Anyone can be affected by COVID-19 and it can cause serious illness and death at any age
COVID-19 spreads through the same way as other corona viruses do, mainly through droplet infection.
SARS-CoV-2 is one of the types of corona virus and has many variants which are discussed below.

First of all, let’s understand what is variant and mutation.

Variant: Variants is a viral genome (genetic code) that may contain one or more mutations.

Mutation: A mutation refers to a single change in a virus’s genome (genetic code). Mutations happen frequently, but only sometimes change the characteristics of the virus.

Different Variants of SARS-CoV-2 virus/COVID-19:

1. Alpha variant

Alpha variant was the first publicized variant of corona virus.
Alpha variant emerged in England in September 2020 and designated as variant of concern in December 2020.
It is estimated to be around 50% more transmissible than original SARS-CoV-2 strain.
Symptoms of alpha variant are largely similar to the original variant of SARS-CoV-2.
With available treatment and vaccines, the risk of death from this variant can be highly prevented.

2. Beta variant

Beta variant was first detected in South Africa at the end of 2020 and spread to other countries
The global prevalence of Beta variant is decreasing as other variants are becoming more severe.
Beta variant is also estimated to be 50% more contagious than the original variant but there is little evidence that it is associated with more severe disease.
Those who have recovered from COVID 19 are at more risk of being infected again from Beta variant.
Vaccines provide strong protection against the Beta variant.

3. Gamma variant

Gamma variant was first spotted in the Amazon city of Manaus in December 2020 and also contributed to a surge in cases of COVID-19 in Brazil.
Gamma variant may be 1.7 to 2.4 times transmissible than non-variants of concern
People who have recovered from COVID-19 can only afford 54% to 79% of protection against reinfection from Gamma variant.
Existing vaccine of COVID-19 work well to provide against this variant.

4. Delta variant

Delta variant was first spotted in India in December 2020 and caused a huge surge in cases in mid-April 2021
It rapidly took over the existing variants to become the dominant variant in many countries
It is estimated to be 80-90% more transmissible than alpha variant and roughly twice as transmissible than the Wuhan variant
This variant is considered to be the more infectious and spread more rapidly than any other variant even on those who have been vaccinated
This has more than a dozen of variant. A delta plus variant was also reported to be seen in Nepal and some other South Asian countries.
This can be severe to those who haven’t been vaccinated and to those who have been vaccinated a long time ago.

Attributes:

Increased transmissibility29
Nearly all lineages designated as Delta are susceptible to Emergency Use Authorization (EUA) monoclonal antibody treatments. AY.1 and AY.2 lineages are not susceptible to some monoclonal antibody treatments.7, 14
Reduction in neutralization by post-vaccination sera

5. Kappa Variant

Kappa is referred to as sibling of delta variant.
It was seen along delta variant in India in few cases.
It is not popularly known as much as delta as delta has been dominated while the presence of Kappa was very few.

6. Omicron Variant

It was identified in Botswana and South Africa in late November 2021 and was considered as variant of concern by the U.S. government SARS-CoV-2 Interagency Group (SIG)
It was rapidly spread into many countries with high transmissibility
It has large number of mutations with numerous high concerns mutants
This has high risk of reinfection in comparison to other variants
Breakthrough infection are possible even after full vaccination but vaccination and booster doses are still effective for its prevention, hospitalization and deaths

Attributes:

Potential increased transmissibility
Potential reduction in neutralization by some EUA monoclonal antibody treatments
Potential reduction in neutralization by post-vaccination sera

Classes of SARS-CoV-2 Variant:

The U.S. government SARS-CoV-2 Interagency Group (SIG) Variant classification scheme defines four classes of SARS-CoV-2 variants:

1. Variant Being Monitored (VBM)

Alpha (B.1.1.7 and Q lineages)
Beta (B.1.351 and descendent lineages)
Gamma (P.1 and descendent lineages)
Epsilon (B.1.427 and B.1.429)
Eta (B.1.525)
Iota (B.1.526)
Kappa (B.1.617.1)
1.617.3
Mu (B.1.621, B.1.621.1)
Zeta (P.2)

2. Variant of Interest (VOI)

Currently, no SARS-CoV-2 variants are designated as VOI.

3. Variant of Concern (VOC)

Delta (B.1.617.2 and AY lineages)
Omicron (B.1.1.529 and BA lineages)

4. Variant of High Consequence (VOHC)

To date, no variants of high consequence have been identified in the United States.
Vaccines approved and authorized for use in the United States are effective against the predominant variant circulating in the United States and effective therapeutics are available. CDC continues to monitor all variants circulating within the United States.