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COVID-19: UK Escalates Offshoot of B.1.617 Variant as ‘Variant of Concern’

COVID-19: UK Escalates Offshoot of B.1.617 Variant as ‘Variant of Concern’

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The UK government has reclassified a descendant of the B.1.617 variant, which was first identified in India, as a ‘variant of concern’, from the earlier classification of ‘variant of interest’. The government said this decision was taken after a rise in cases in the UK and evidence of community transmission.

The descendant refers to B.1.617.2, a sub-lineage of the B.1.617 variant.

The evidence also reportedly suggests that B.1.617.2 is at least as transmissible as the B.1.1.7 variant, which was first identified in the UK. “The other characteristics of this variant are still being investigated,” the government said in a statement.

The statement adds that there is currently insufficient evidence to indicate that the variants recently detected in India can cause more severe disease or render the vaccines currently deployed any less effective.

Public Health England, an autonomous government organisation, is carrying out laboratory tests in collaboration with academic and international partners to “better understand the impact of the mutations on the behaviour of the virus”, the statement added.

Instances of people infected with B.1.617.2 increased from 202 to 520 in the past week, the UK government added, saying almost half the cases are related to travel or contact with a traveller. The UK has already placed India on the red list, which prevents non-citizens or non-permanent residents from travelling to the country.

According to the US Centres for Disease Control and Prevention (CDC), a ‘variant of interest’ is defined as follows:

“A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity.”

The CDC has listed the B.1.617 variant and its three sub-lineages as ‘variants of interest’ in the US. The UK reclassification pertains to the second sub-lineage, B.1.617.2. A sub-lineage pertains to a branch of a branch of the virus’s mutation tree. That is, imagine the virus’s ‘original’ variant to be the tree trunk. Each new variant, like B.1.617, B.1.1.7, B.1.351 and P.1, is a branch. The B.1.617.2 sub-lineage is an offshoot of the B.1.617 branch.

A ‘variant of concern’ is defined thus:

“A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.”

In the US, the B.1.1.7 variant (first identified in the UK), B.1.351 (South Africa), P.1 (Brazil) and B.1.427 .429 (both in California) as ‘variants of concern’.

There is a third level, the highest – ‘variant of high consequence’, defined thus:

“A variant of high consequence has clear evidence that prevention measures or medical countermeasures (MCMs) have significantly reduced effectiveness relative to previously circulating variants.”

No variant of SARS-CoV-2 has thus far been placed in the third category.

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