The Delta variant, or B.1.617.2, which was first identified in India in October 2020, has now become the leading covid strain in the UK, presently reporting for more than 90% of cases there.

In the US, too, the number of Delta variant cases are speedily growing, up from 10% of the total Covid-19 cases last week to 20% this week. According to a Financial Times analysis, the delta variant reports for more than a third of new cases each day in the US.

What is Delta Plus?

The variant, called “Delta Plus” in India, was first reported in a Public Health England bulletin on June 11.

It is a sub-lineage of the Delta variant first detected in India and has obtained the spike protein mutation called K417N which is also found in the Beta variant first identified in South Africa.

Some scientists concern that the mutation, joined with current features of the Delta variant, could make it more infectious.

“The mutation K417N has been of interest as it is present in the Beta variant (B.1.351 lineage), which was reported to have immune evasion property,” India’s health ministry said in a declaration.

Shahid Jameel, a top Indian virologist, said the K417N was known to decrease the efficiency of a mixture of therapeutic monoclonal antibodies.

Where all has it been found?

As of June 16, at least 197 cases had been detected in 11 countries — Britain (36), Canada (1), India (8), Japan (15), Nepal (3), Poland (9), Portugal (22), Russia (1), Switzerland (18), Turkey (1), the United States (83).

India said, on Wednesday, around 40 cases of the variant have been detected in the states of Maharashtra, Kerala and Madhya Pradesh, with “no significant increase in prevalence”. The initial case in India is from a sample taken on April 5.

Britain said its first 5 cases were sequenced on April 26 and they were contacts of individuals who had travelled from, or transited through, Nepal and Turkey.

No deaths were accounted among the UK and Indian cases.

What are the worries?

Research is ongoing in India and world-wide to test the efficiency of vaccines against this alteration.

“WHO is tracking this variant as part of the Delta variant, as we are doing for other Variants of Concern with additional mutations,” the World Health Organization (WHO) said in a declaration sent to Reuters.

“For the moment, this variant does not seem to be common, currently accounting for only a small fraction of the Delta sequences…Delta and other circulating Variants of Concern remain a higher public health risk as they have demonstrated increases in transmission,” it said.

But India’s health ministry cautioned that regions where it has been found “may need to enhance their public health response by focusing on surveillance, enhanced testing, quick contact-tracing and priority vaccination.”

There are doubts that Delta Plus would impose another wave of diseases on India after it emerged from the world’s worst surge in cases only recently.

The mutation itself may not lead to a third wave in India — that also depends on Covid-appropriate behaviour, but it could be one of the reasons,” said Tarun Bhatnagar, a scientist with the state-run Indian Council for Medical Research.