SARS-COV-2 δ variant drives the pandemic in India and Europe via two subvariants

SARS-COV-2 evolution generates different variants and drives the pandemic. As the current main driver, {delta} variant bears little resemblance to the other three variants of concern, raising the question what features future variants of concern may possess. To address this important question, I compared different variant genomes and specifically analyzed {delta} genomes in the GISAID database for potential clues. The analysis revealed that {delta} genomes identified in India by April 2021 form four different groups (referred to as {delta}1, {delta}2, {delta}3 and {delta}4) with signature spike, nucleocapsid and NSP3 substitutions defining each group. Since May 2021, {delta}1 has gradually overtaken all other subvariants and become the dominant pandemic driver, whereas {delta}2 has played a less prominent role and the remaining two ({delta}3 and {delta}4) are insignificant. This group composition and variant transition are also apparent across Europe. In the United Kingdom, {delta}1 has quickly become predominant and is the sole pandemic driver underlying the current wave of COVID-19 cases. Alarmingly, {delta}1 subvariant has evolved further in the country and yielded a sublineage encoding spike V36F, A222V and V1264L. These substitutions may make the sublineage more virulent than {delta}1 itself. In the rest of Europe, {delta}1 is also the main pandemic driver, but {delta}2 still plays a role. In many European countries, there is a {delta}1 sublineage encoding spike T29A, T250I and Q613H. This sublineage originated from Morocco and has been a key pandemic driver there. Therefore, {delta} variant drives the pandemic in India and across Europe mainly through {delta}1 and {delta}2, with the former acquiring additional substitutions and yielding sublineages with the potential to drive the pandemic further. These results suggest a continuously branching model by which {delta} variant evolves and generates more virulent subvariants.