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The 'delta plus' variant is a mutated version of the more aggressive B.1.617.2 strain that drove the second wave of infections in India. It is characterised by the K417N mutation in the spike protein of the SARS-CoV2 virus that causes the COVID-19 disease.
The spike protein is what helps the virus enter and infect human cells, and the K417N mutation has been associated with immune escape, or evasion, that leaves it less susceptible, or more immune, to the vaccine or any form of drug therapy.
The government on Tuesday said the 'delta plus' variant had been around since March this year. It is not, however, a variant of concern at this point, Dr VK Paul, Member (Health), NITI Aayog, said. "Its presence had been detected and submitted to global data system," he added.
According to Public Health England, 63 B.1.617.2 genomes with the K417N mutation have been identified so far, six of which are from India. There are 36 confirmed 'delta plus' cases in the UK and it accounts for around six per cent of cases in the US. Two UK cases were registered more than 14 days after the second vaccine dose, making them 'breakthrough' infections.
However, there is no cause for concern as reports of the new variant are still low and there is no indication, as yet, about the severity of the disease, Anurag Agrawal, Director of Delhi's CSIR-Institute of Genomics and Integrative Biology (IGIB), said. He also said blood plasma from a number of fully vaccinated individuals would have to be tested against this variant to establish if it shows any significant level of immune escape.
Vinod Scaria, another CSIR-IGIB scientist, said the K417N variant was more frequent in Europe, America and other Asian countries at this time. He also said travel histories were not immediately available, meaning it is unwise to assume how far it may have spread.
The 'delta plus' variant is resistant to the monoclonal antibody cocktail recently authorised in India. These cocktails - Casirivimab and Imdevimab - are designed to block the virus from attaching to human cells and entering the body, and are similar to antibodies that the human body naturally produces to defend itself against the disease.
As a counterpoint, Vineeta Bal, a guest faculty at Pune's Institute of Science Education and Research, told PTI resistance to therapy did not indicate severity. She also said the quality and quantity of neutralising antibodies generated by an individual infected with the new variant is unlikely to be affected because of the mutation.
The 'delta' variant of COVID-19 - first reported in India in October last year - is already between 40 and 50 per cent more infectious than the 'alpha' version first reported from the UK and is, according to a (not yet peer-reviewed) study by AIIMS, likely behind the majority of breakthrough infections in India.
Studies differ on just how effective vaccines currently in India - Covishield and Covaxin - are in protecting against the 'delta' variant. The AIIMS study indicated it might not protect people even after the second dose, while a research letter published in The Lancet said Covishield (the AstraZeneca shot) provided 79 per cent protection after two doses.
With input from PTI