Coronavirus | AY4.2 variant ‘infrequent’ in India: INSACOG

AY4.2 responsible for a ‘slowly increasing’ proportion of cases in the U.K., according to Public Health England

Updated - October 27, 2021 11:48 pm IST

Published - October 27, 2021 09:44 pm IST - NEW DELHI:

The recent rise in AY4.2 in genomic surveillance “needs to be interpreted with caution”.

The recent rise in AY4.2 in genomic surveillance “needs to be interpreted with caution”.

The latest mutation of the coronavirus variant, AY4.2, which has been linked to a rise in cases in the United Kingdom, is “very infrequent” in India, according to a weekly report by the India SARS-CoV-2 Genome Consortium (INSACOG), the body that tracks the emergence of new variants, on Wednesday.

AY4.2 was responsible for a “slowly increasing” proportion of cases in the U.K., according to Public Health England (PHE) on October 22. It is also present in multiple other countries and is seen in travellers to the U.K. from a large number of countries. It is not clear where AY4.2 originated or when. This lineage of the coronavirus has the mutations of Delta — the dominant global variant — and AY.4, a sub-lineage. The characteristic mutations were S:A222V on the spike protein; and Y145H, which were mutations are in the N terminal domain, or the region of the coronavirus that doesn’t bind to the human cells.

It isn’t yet clear what specific advantage these mutations confer to AY4.2 that aid its spread. However, in terms of its severity, it is still as potent as Delta. The PHE has said it has commissioned studies to establish the increase in severity, if at all, that AY4.2 confers.

As of October 21, 2021, there were 15,120 cases in England linked to AY4.2.

VUI-21OCT-01 (the variant under investigation classified on October 21, 2021) accounted for 3.8%, 5.2% and 5.9% of Delta cases in England in the weeks beginning September 19, September 21 and October 3, 2021, respectively, according to the PHE.

INSACOG, in its latest bulletin made public on Wednesday, said that the recent rise in AY4.2 in genomic surveillance “needs to be interpreted with caution” as there were technical issues with the detection of the Y145H mutation. Most sequences from India that are being classified as AY4.2 by PANGO, one of the global classification systems for coronavirus lineages, have only either Y145H or A222V in the spike, and not both the mutations appearing together.

Delta (B.1.617.2) and its related sublineages (AY that numbered till 35) continues to be the main Variant of Concern (VOC) in India. No new VOI (Variant of Interest) or VOC are noted in India, according to the INSACOG. Many cases earlier labelled as AY.4 were now reclassified at AY.33. “It has been noted that due to greater diversity of Delta in India, PANGO classifications may sometimes be inaccurate, especially for new sub-lineages. INSACOG is thus further examining the data on AY.33,” their report noted.

So far about 107,000 coronavirus samples have been sequenced in India, of which 88,000 have been “analysed” to establish their lineages. India has been seeing an overall decline in new cases with less than 15,000 cases being added every day. Though there’s been a spike in confirmed deaths, these are mostly due to backdated deaths in Kerala being added to the official tally.

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