What are the SARS-CoV-2 variants ?

What are the SARS-CoV-2 variants ?

Information and image taken from WHO website on 30 Jun 2021 

All viruses, including SARS-CoV-2, the virus that causes COVID-19, change over time. Most changes have little to no impact on the virus’ properties. However, some changes may affect the virus’s properties, such as how easily it spreads, the associated disease severity, or the performance of vaccines, therapeutic medicines, diagnostic tools, or other public health and social measures. Variants that changed with the above factors are considered “Variants of Concern (VOC)”.

SARS-CoV-2 Variants of Concern (VOC), updated 15 June 2021 in WHO website

WHO label 

Pango  
lineage 

GISAID clade/lineage

Nextstrain  
clade 

Earliest documented  
samples 

Date of designation 

Alpha 

B.1.1.7 

GRY (formerly GR/501Y.V1) 

20I (V1) 

United Kingdom,  
Sep-2020 

18-Dec-2020

Beta 

B.1.351 

GH/501Y.V2 

20H (V2)

South Africa,  
May-2020 

18-Dec-2020

Gamma 

P.1 

GR/501Y.V3 

20J (V3)

Brazil,  
Nov-2020 

11-Jan-2021

Delta 

B.1.617.2  

G/478K.V1 

21A

India,  
Oct-2020 

VOI: 4-Apr-2021 
VOC: 11-May-2021 

Source: https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/

 

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What about the Delta variant?
What about the Delta variant?

Delta variant (B.1.617.2 lineage)

Origin

This lineage was first identified in India in December 2020 and has become one of the prevalent variants there and in several other countries.

Transmissibility

Data from the United Kingdom suggest that Delta variant is more transmissible than Alpha variant; the proportion of SARS-CoV-2 infections caused by Delta variant rose as that caused by Alpha variant declined.  Additionally, a study in Japan said Delta variant was associated with 1.23 times higher transmissibility than Alpha variant.

Risk of hospitalization

The same report also suggests that Delta variant is associated with a higher risk of hospitalization than Alpha variant. Some reports said the Delta variant was associated with significant higher viral load.

Vaccination against Delta

Studies suggest that vaccine effectiveness of full courses two doses of Pfizer-BioNTech COVID-19 vaccine (BNT162b2 - Comirnaty) or AstraZeneca vaccine(ChAdOx-1/ADZ1222 - Vaxzevria) against symptomatic disease was high for Delta variant (88% for Pfizer-BioNTech and 67% for AstraZeneca) but slightly less than for Alpha variant; effectiveness against Delta variant after a single dose of each vaccine was low.

Delta, on 29 Jun 2021 reported in 96 countries globally, continues to be reported in new countries across all WHO Regions. Virus evolution continues to be expected, and the more SARS-CoV-2 circulates, the more opportunities it has to evolve. Reducing transmission through established and proven disease control methods such as vaccination are crucial to reduce the occurrence of mutations that have negative public health implications.

Covid-19 Vaccination

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