New Delta variant AY.4.2 detected in India; what we know so far

Over the past few days, several cases of an offshoot of Delta variant — called AY.4.2 — have surfaced in India, putting health authorities on alert.

On Saturday, seven cases related to this variant were detected in Indore in a genome sequencing report released by the National Centre of Disease Control (NCDC). Besides, the AY.4 variant has also been detected in 1 percent samples in Maharashtra, the first state to report cases of this new subtype of the Delta variant.

This new strain comes from the Delta variant (B.1.617.2) of the novel coronavirus that fuelled the second wave of the pandemic in India in April-May this year. The AY.4.2 variant was first identified by the Health Security Agency of the United Kingdom. Some researchers have said that the AY.4.2 strain could be nearly 10 percent more transmissible than the original Delta variant.

In a briefing on October 22, the UK Health Security Agency said AY.4.2 accounted for a "slowly increasing proportion of cases in the UK". The agency added that this sublineage accounted for approximately 6 percent of all sequences generated in the UK. The observation comes in the wake of the UK recording one of the highest absolute numbers of new COVID-19 cases in any country.

Apart from the UK, the new variant is also ratcheting up infections in the US, Germany, France, Italy, Russia, and Israel. While the cases of the AY.4.2 variant have surfaced in several countries, its origin is not yet known.

According to the UK agency, the AY.4.2 is distinguished by two key spike mutations — A222V and Y145H. While A222V is found across most Delta lineages, Y145H is still being studied. For now, the UK has declared the AY.4.2 as the 'variant under investigation'.

On the other hand, INSACOG, a consortium of leading Indian institutes engaged in SARS-COV 2 genome sequencing, has put the AY.4.2 strain under the 'variant of interest' category. The body has said that there is "very little knowledge about its transmissibility, or whether it could cause severe infection and whether it can cause breakthrough infections".

Meanwhile, the AY.4.2 is yet to be designated by the World Health Organisation (WHO). So far, the WHO has identified four variants of concerns — Alpha (B.1.1.7, first reported in the UK), Beta (B.1.351, South Africa), Gamma (P.1, Brazil), and Delta (B.1.617.2, India).