A COVID-19 variant — the Delta variant — is quickly becoming the most widely spread strain of the virus across the globe, with rising cases in China and the United Kingdom. First detected in India, over 100 new cases caused by the Delta strain — also known as B.1.617.2 — have been reported in China's Guangdong province. Meanwhile, British health minister Matt Hancock has reported that the newest iteration of the virus is 40% more transmissible than B.1.1.7, the previous strain that was widely spread in the U.K.
It has about a 40% higher transmission rate compared with alpha, which already had a 50% higher transmissibility than the original strain of the virus.
This is delta strain had of the mutations that contributed to the loss of response to some antibodies, including those produced by the vaccines. We do know that delta is less sensitive than alpha to antibodies generated by the vaccines.
Also, data from Public Health England shows that the first dose of the Pfizer Inc.-BioNTech SE and AstraZeneca Plc vaccines provide only about a 30% protection against delta, though this rises to at least 88% after the second dose of the Pfizer vaccine and 60% after the second dose of the Astra vaccine (this is likely to rise with more time for second doses to take effect in Britain).
The real risk is when you consider the broader population, where many people are either unvaccinated or only have one dose of the vaccine, combined with delta’s higher transmissibility and disease severity.
How did Delta variant mutate into Delta Plus
PHE's report said the Delta-AY.1 version was found through routine scanning of variations in Delta. A small number of detected sequences had acquired the spike protein mutation K417N, it said.
Scientists attribute the earliest such sequence to Europe in late March with 127 sequences added from Europe, Asia and America, said Dr Vinod Scaria, clinician and computational biologist at Delhi's Institute of Genomics and Integrative Biology.
Several genomes now available across the world were part of the AY.1 or B.1.617.2.1 lineage. The sequences are mostly from Europe, Asia and America, said Scaria.
The K417N mutation is also found in Beta or B.1.351, which is regarded as a variant of concern.
Delta Plus resistant to antibody cocktail
Scaria said an important point to consider regarding K417N was "evidence suggesting resistance to monoclonal antibodies Casirivimab and Imdevimab".
This cocktail recently received emergency-use authorization in the country from the Drug majors and Ciplas have priced the antibody cocktail at a steep Rs 59,750 per dose.
Similar to antibodies which are proteins that the body naturally produces to defend itself against the disease, monoclonal antibodies are artificially created in a lab and tailor-made to fight the disease they treat.
Casirivimab and Imdevimab are monoclonal antibodies that are specifically directed against the spike protein of SARS-CoV-2 and designed to block the virus' attachment and entry into human cells.
Scaria also indicated the mutation may be associated with the ability to escape the immune response against the virus.
Allaying fears, immunologist Vineeta Bal noted that while there may be some setback in the use of commercial antibody cocktail due to the new variant, resistance to the therapy is not an indication of higher virulence or severity of a disease.
She also noted that the quality and quantity of neutralising antibodies, responsible for defending cells from pathogens, generated in the individual infected with the new variant is unlikely to be affected because of the mutation.
“Thus in individuals catching infection with the new variant, it may not be a matter worth worrying,” she added.
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