The Brihanmumbai Municipal Corporation (BMC) has decided to collect 1000 sewage water samples for RT-PCR testing to understand Covid-19 variants in the community. Experts said unlike other respiratory viruses, RNA [ribonucleic acid] of SARS-CoV-2 and other coronaviruses can be detected in human faeces.

Next week, the BMC is all set to test sewage samples from the city’s outfalls and conduct RT-PCR tests to study the presence of Covid variants. Samples that will test positive for Covid will undergo genome sequencing at the lab in Kasturba hospital. BMC officials said waste water surveillance will help them plan future policies and interventions.

“This is a new exercise that we plan to do to understand the variants of Covid-19 in the community. The sewage water samples testing positive in RT-PCR test will be sent for genome sequencing,” said Suresh Kakani, additional municipal commissioner, BMC.

He further explained, “We have the genome sequencing facility and so far, we have collected samples for genome sequencing from community, hospitals and people who have died of Covid-19. We now want to check the sewage water samples that will help us plan future policies and interventions.”

Since August 2021, BMC has carried out a total 10 surveys for genome sequencing to understand the pattern of Covid-19 spread in the community. In the latest survey, which was announced early this month, 237 samples that BMC’s health department had collected from patients belonging to different age groups and gender, were positive for the Omicron variant or its other subtypes.

Earlier, the Indian Institute of Technology Gandhinagar (IIT-Gn) had joined a global consortium of 51 premier universities and research institutes to undertake surveillance of sewage water to help determine and quantify excretion of the Sars-Cov-2 virus, which caused Covid-19. Recent studies have reported that in 27% to 89% of patients, the infection is accompanied by persistent shedding of virus RNA in stool.