Amid a surge in Covid cases across Maharashtra and detection of sub-lineages of the Omicron variant, the state health department has asked all the civic corporations of 36 districts to start genome sequencing of sewage water to monitor variants of coronavirus.
This comes after 89 percent of Mumbai's samples were detected with BA.2 and BA.2.38 – both sub-variants of Omicron, as per the recent genome sequencing report released by the Brihanmumbai Municipal Corporation (BMC).
Sewage surveillance is known to help in the early identification of any impending wave of Covid and in keeping track of the emergence of new variants of SARS-CoV 2, if any, to initiate local public health actions.
The BMC had carried out genome sequencing of 364 samplesattheKasturbaLaboratory between June 1 and 18, which revealed49per cent were infected with the BA.2.38 variant and 40 per cent with the BA.2 variant. Only 5 per cent had BA.5 variant infections while less than 2 per cent indicated the BA.4 variant.
Senior officials from the state health department said they have been monitoring cases closely and have instructed districts to conduct genome sequencing of sewerage water to understand new Covid variants following the surge. “We have been getting sub-lineages of Omicron variants across Maharashtra but all are milder.
However, we need to keep a close watch to understand if there are any new sub-lineages or variants which can be the possible reason for this spike in cases. We need to conduct a viral load analysis of waste water which will help us understand viruses and their mutations,” said a civic health official.
According to experts, SARS CoV-2 virus' RNA (ribonucleic acid), like other coronaviruses, can be detected in human excreta. Genome sequencing of sewage water samples helps in detecting the presence of Covid in an area early. Such tracking of wastewater helps in the rapid identification of variants in the community.
Dr Trupti Gilada, infectious disease specialist, Masina Hospital, said the predominant variant in India continues to be BA.2 and BA.2.38. “BA.4 and BA.5 share an origin with earlier Omicron strains and are probably offshoots of BA.2,” she said.
“But the rise of BA.4 and BA.5 seem to stem, instead, from their ability to spread faster than other circulating variants as also their capacity to infect people who were immune to earlier forms of Omicron and other variants. Data from other countries has shown that BA.2 in public databases may actually be BA.4 or BA.5.
It is actually important to re-analyse our database too,” she added. Dr Lancelot Pinto, consultant pulmonologist and epidemiologist at P D Hinduja Hospital said at present, BA.4 and BA.5 appear to be causing a small proportion of the overall infections, but this could change, as seen in the latest waves occurring in South Africa and Portugal.
“We need to monitor the situation in these countries closely, as it is hypothesised that these sub-variants could be more transmissible and affect lung tissue (as opposed to the upper respiratory tract) more,” he said. Mumbai reported 2,771 new Covid cases, with the highest single-day spike recorded since January 22, when 3,558 cases were recorded in a single day.
The total of Covid count in the city has now touched 11,07,371 cases. Maharashtra also recorded its highest single-day rise in cases on Sunday, with 6,493 new infections being recorded in the last 24 hours, pushing its tally to 79,62,666,with1,47,905 fatalities.