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?

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.