The decline in daily new infections across India has prompted INSACOG, the consortium of labs focussed on sequencing coronavirus variants, to “prioritise” new surveillance approaches.
In a bulletin dated 11th October, but made public on Monday, INSACOG (India SarsCov2 Genome Consortium) notes: “In view of currently declining cases and importance of early detection of increased transmission in the future, INSACOG will prioritise developing and expanding a SARS CoV2 sewage surveillance program.”
The CSIR-Centre for Cellular and Molecular Biology, which is also part of the INSACOG network, has since early 2020 been collecting sewage from large drains in cities to check for the presence of the virus. Because a large fraction of those afflicted by the virus are asymptomatic but are carriers of infection, their body fluids and stool often contain traces of the virus. Finding large proportions of it in public drains can often be a precursor to a fresh outbreak, with a rise in symptomatic infections.
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Exposure to virus
A study on these lines in Hyderabad using this approach had estimated that nearly 6% of the city may have been exposed to the virus from March to August 2020. Several such studies have been conducted by various institutions from Pune to Lucknow.
The INSACOG currently analyses a fixed fraction of coronavirus samples sourced from hospitals and other community settings.
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New variants
India has been observing a steady decline in new infections with a seven-day average of 16,000 cases a day. The all-time low, since the first wave abated in February, was around 11,000 daily. It was after this decline that the second wave started, primarily led by the emergence of new variants such as Alpha, Kappa and Delta. “Delta (B.1.617.2 and AY.x) continues to be the main VOC (Variant of Concern) in India. No new VOI (Variant of Interest) or VOC are noted in India,” the communique notes.
As of last week, 104,441 coronavirus samples have been sequenced for their genetic structure, though the bulk of these are from two States: Maharashtra and Kerala.