NEW DELHI: While there have been no cases of new Covid-19 variants — Mu, South African C.1.2 — in India so far, the national genomic surveillance consortium on Friday called for stronger implementation of existing recommendations on sequencing of positive samples from international travellers.
The Indian SARS-CoV-2 Genomics Consortium (INSACOG) weekly bulletin shows that Delta and Delta sub-lineages continue to be the main VOC (variants of concern) in India and AY.4 is the most frequently seen sub-lineage in recent sequences from India, as well as globally. Of the 63,774 samples of VOC and Variants of Interest (VOI) sequenced by INSACOG, 42,833 were Delta.
The WHO added B.1.621 (including B.1.621.1) to the list of VOI on August 30 and gave it the designation “Mu”. It has mutations that indicate potential immune escape properties. There appears to be a reduction in neutralization capacity of convalescent and vaccine sera, similar to what was seen for the Beta variant, but this needs to be confirmed.
WHO has also added C.1.2 as a new VOI. C.1.2 is a sub-lineage of the C.1 variant seen in South Africa, which did not spread globally. The C.1.2 variant seems to have undergone many mutations in a short time, and contains mutations of all three types that have previously been found to be important for transmissibility and immune escape.
The INSACOG data portal has started including sub-lineage labels up to AY.12 to enable better tracking. The latest update takes the classification to AY.25, with the following notification — “as previously outlined for AY.4-AY.12, each of the new AY.13-AY.25 lineages shows significant geographical clustering and these lineages have been designated to help researchers track the virus on a finer scale. However, their designation does not imply any functional biological difference from B.1.617.2 and, like B.1.617.2, they correspond to the WHO-defined Delta variant.”