The newly emergent B.1.617.2 variant, named as the Delta by World Health Organisation, has been found to be behind the deadly second wave of coronavirus pandemic in India, according to a government study.
The UK and Singapore have also flagged the variant as dangerous and have imposed curbs to check its spread. It is of the same B.1.617 lineage first reported in India.
What is the Delta variant? How’s it different from B.1.617 or Kappa?
B.1.617, the variant originally identified in October 2020, was found to be behind 60 per cent of the cases in Maharashtra by mid-February 2021, when the second wave was rearing its head in the country. The B.1.617.2 is what is known as a sub-lineage of B.1.617, which has also spawned two other sub-lineages: B.1.617.3, the first sub-lineage to be detected, and B.1.617.1.
B.1.617 was earlier this month classified as a variant of concern by WHO. But in recent weeks, it is the B.1.617.2 sub-lineage that has triggered widespread alarm. The UK last month termed it a variant of concern and behind the surging cases.
The prominent change in these variants and sub-lineages of the novel coronavirus is in the spike protein, which helps it to invade and latch on to human cells. In fact, the Delta variant has pushed out the Kent variant and has become the dominant strain in the UK.
What about the Delta variant in India?
It is reported that the variant has become the most common variant in India. About a third of the samples from India submitted to flu virus repository GISAID for virus sequencing were linked to the Delta variant. In fact, this lineage is now by far the most prevalent in new cases in India, the data suggests with B.1.617 and B.1.617.2 together making up 60 per cent of the samples from India in the last 60 days.
Reports say that Bihar, Chhattisgarh and Jharkhand have seen a large number of cases linked to the Delta variant.
The Delta variant - or the B.1.617.2 strain - is “more infectious" than the Alpha variant first detected in Kent, UK, says the study by scientists of the Indian SARS COV2 Genomic Consortia and the National Centre for Disease Control. The study was launched to investigate what caused the second surge.
The Delta variant is, in fact, 50 per cent more contagious than the Alpha strain, the study says.
Is the new variant more powerful? Will vaccines work against it?
While health experts have suggested that the Delta variant may be up to 50 per cent more transmissible than its predecessor, more data is awaited to accurately determine whether it causes a more severe disease.
The UK Health Secretary Matt Hancock said last month that there was evidence to suggest that vaccines already out are effective against the Delta sub-lineage. Trust in vaccines to fend off this variant is also echoed by UK’s decision to fast-track the vaccination process by reducing the gap between two doses. Hancock had added that data from Oxford University and preliminary reports from India showed that vaccines are effective against the variant.