Recognized Variants of SARS-CoV-2

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According to Centers for Disease Control and Prevention (CDC), there are about 19 variants of SARS-CoV-2 and it is underway of its mutation [1,2]. The mutation in the genetic sequence drives the way for ongoing mutation, especially with new amino acid sequences in the protein encoding spike proteins. The altered sequences in the amino acid have given rise to new variants overtime. The United States (US) based interagency has categorized Variants into one of there categories, comprising Variant of Interest (VOI), Variant of Concern (VOC) and Variant of High Consequence (VOHC). The National Institutes of Health (NIH), the Food and Drug Administration (FDA), the Biomedical Advanced Research and Development Authority (BARDA), and the Department of Defense (DoD) formed the SARS-CoV-2 Interagency Group (SIG), which collaborated with the CDC.

 

The Alpha (B.1.1.7), beta (B.1.351), gamma (P.1), and Delta (B.1.617.2) have been classified to be the variants of concern in United States wherein no variants of high consequence have been reported [2].

Recognized Variants of SARS-CoV-2

S. No.	WHO Label	Pango Lineage	Country of Origin	Target of Mutation	Designated Date
1	Alpha	B.1.1.7	United Kingdom (September, 2020)	Spike Protein	18-December-2020
2	Beta	B.1.351 B.1.351.2 B.1.351.3	South Africa (May, 2020)	Spike Protein	18-December-2020
3	Gamma	P.1 P.1.1 P.1.2	Brazil (November, 2020)	Spike Protein	11-January-2021
4	Delta	B.1.617.2 AY.1 AY.2	India (October, 2020)	Spike Protein	Variant of Interest: 4-April-2021 Variant of Concern: 11-May-2021
5	Epsilon	B.1.427 B.1.429	Spike Protein	United States
6	Eta	B.1.525	Spike Protein	United Kingdom/Nigeria
7	Iota	B.1.526	Spike Protein	United States ( November,2020)
8	Kappa	B.1.617.1	Spike Protein	India ( India,2020)
9	-	B.1.617.3	Spike Protein	India ( October,2020)
10	Zeta	B.1.617.1	Spike Protein	Brazil ( April,2020)

The B.1.1.7 has been found to have a high transmission rate, with 17 adherent mutations in its genome alone, eight of which have been identified exclusively on the basis of spike protein [3]. Moreover, another extremely infectious variant P.1 has elucidated a critical health care system of Brazil. According to the Moderna, their vaccine has been reported to be effective in B.1.351 and B.1.1.7.  However, the South African Variant was reported with substantial reduction in the neutralizing antibodies [3]. Another vaccine developing company Pfizer revealed to have their vaccine effective against B.1.1.7 but still the reports need to be aggravated for better generalizations [3]. Researchers and public health organizations throughout the world are using the Pango nomenclature to track the transmission and spread of SARS-CoV-2, including variants of concern [4]. The variants based on the SIG has been illustrated below.

 

S. No.	Classification of Variants	Definition	Pango Lineage
1	Variants of Interest	A genetic variation linked with alterations in receptor binding, decreased neutralization by antibodies produced against past infection or immunization, reduced therapeutic efficacy, possible diagnostic impact,or anticipated increase in transmissibility or disease severity.	B.1.427
2	Variant of Concern	A variant with evidence of increased transmissibility, more severe disease (e.g., more hospitalizations or deaths), substantial decrease in neutralization by antibodies produced during previous infection or vaccination, reduced effectiveness of treatment options or vaccines, or diagnostic detection inadequacies.	B.1.1.7 B.1.351 P.1 B.1.617.2
3	Variant of High Consequence	In comparison to previously circulating variations, a variant of high consequence has clear evidence that preventive interventions or medical countermeasures (MCMs) are considerably less effective.	Nil

References

S. No.	References
1	https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/
2	https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-info.html
3	https://doi.org/10.1016/S0140-6736(21)00298-1
4	https://cov-lineages.org/