The highly transmissible Delta variant, first identified in India, has been a major force driving the last wave of COVID-19 cases seen across the world. Now, India is raising the alarm on another problem: the Delta plus variant. 

On Tuesday, June 22, India's health ministry described the Delta plus variant, also known as Delta-AY.1, as a “variant of concern.” However, some scientists have said it’s too early to say whether this new mutant fits the definition of a “variant of concern” and further research is needed before panic ensues. 

The variant of SARS-CoV-2 is much like the Delta variant but features a new mutation to the Receptor Binding Domain (RBD) called K417N, according to authorities in India. So far, 22 cases of the Delta Plus variant have been reported in a number of districts across the Indian states of Maharashtra, Kerala, and Madhya Pradesh. Public Health England published some information on the Delta plus variant early this month, noting there at least 63 instances of the variant reported as of June 7, 2021: Canada (one case) Germany (one), Russia (one), Nepal (two), Switzerland (four), India (six), Poland (nine), Portugal (12), Japan (13), the US (14).

“The acquisition of the K417N in the Delta-AY.1 variant is a worrying development, as we know that this mutation is found in the South African (beta, B.1.351) variant that has enhanced transmissibility as well as significant vaccine escape properties," Dr Julian Tang, Honorary Associate Professor/Clinical Virologist in Respiratory Sciences from the University of Leicester in the UK, commented on June 18.

“It is likely that this K417N mutation together with the L452R mutation present in all the Indian variants may enhance the delta-AY.1’s vaccine escape properties.” 

Health authorities in India say they’ve carried out lab tests on the Delta plus variant and found it’s likely to be more transmissible, binds more easily to lung cells, and is possibly more resistant to monoclonal antibody therapy. 

However, many experts have said it’s too soon to know whether the Delta plus variant should be considered a “variant of concern” as there’s very little real-world data currently at hand.  

"There is no data yet to support the variant of concern claim," Dr Gagandeep Kang, a virologist and the first Indian woman to be elected Fellow of the Royal Society of London, told BBC News. "You need biological and clinical information in order to consider whether it is truly a variant of concern."

"You need to study a few hundred patients who are sick with this condition and variant and find out whether they are at greater risk of greater disease than the ancestral variant," Dr Kang added.

Even aside from this problematic new mutation, the Delta variant continues to shape the COVID-19 pandemic. By some estimates, the Delta is up to 60 percent more transmissible than the already highly infectious Alpha variant, first identified in the UK in late 2020. Thanks to this high level of transmissibility, the Delta variant now accounts for 99 percent of cases in the UK and represents 20 percent of new cases in the US.