‘Cause for worry’: Expert weighs in on immune escape potential of Delta plus Covid variant

After the emergence of the ‘Delta plus’ variant of coronavirus, experts have raised concern about its ability to evade pre-existing immunity. Earlier this week, scientists said that the highly transmissible Delta variant, first identified in India, has further mutated to form the Delta plus, however, added that there was no immediate cause of concern due to low incidence in the country.

The latest research shows that the Delta plus variant characterised by B.1.617.2 variant acquiring another mutation, K417N, also found in the B.1.351 or Beta variant of concern. The mutation is in the spike protein of Sars-CoV-2, which helps the virus enter and infect the human cells. The earliest sequence of this genome was found in Europe in late March this year.

Experts stressed the need for more studies on the 'Delta plus’ variant before reaching any conclusion on its transmissibility and ability to evade pre-existing immunity, built up either by vaccination or infection with the original Sars-CoV-2 strain.

"The B.1.617.2 or Delta variant of concern has acquired another mutation - K417N - within the receptor-binding domain of the spike protein. This new variant is called Delta or AY.1. This change is of note since this mutation is also found in the B.1.351 or Beta variant of concern," leading virologist Dr Shahid Jameel told news agency ANI.

"So, in a sense, this is the coming together of changes earlier found in two different variants of concern, which are so far the best adapted to immune escape. Whether this new variant will evade pre-existing immunity better than either Delta or Beta remains to be seen. Therefore, it is a cause for worry but not panic. More studies are needed," he added.

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So far, 202 sequences corresponding to the Delta plus variant have been found in 11 countries, with the highest numbers of cases being reported from the United States. India has reported eight cases of Delta plus variant, with three cases from Tamil Nadu and one each from Odisha, Karnataka, Andhra Pradesh, Gujarat, and Maharashtra.

But Dr Jameel cautioned about the low incidence, reminding that the B.1.617 variant, the precursor of the Delta variant, was also seen in very low numbers in India in December 2020 and surged within the next eight to 12 weeks.

"The Indian vaccines have shown three to eightfold reduced efficacy against the Delta and Beta VOCs. Whether this coming together of key mutations would be neutral, additive or more than the sum of both remains to be seen," said Dr Jameel.

(With ANI inputs)