Hyderabad based Centre for Cellular and Molecular Biology (CCMB) is conducting a study taking sewage samples. The CCMB will use sewage/waste water samples to estimate the spread of the infection in a given locality or area. The SARS-CoV-2 in sewage samples is non-infectious, thus making sewage samples suitable for epidemiological studies.
This is according to a joint study taken up by CSIR institutions of Centre for Cellular and Molecular Biology (CCMB) and Indian Institute of Chemical Technology (IICT) after harvesting the sewage samples to estimate the number of potentially infected individuals in the city. It was carried out at 10 Sewage Treatment Plants (STPs) and a gated community with the samples tested using the RT-PCR method.
While viral RNA is detectable in the inlet samples, the outlet (after treatment) samples of STP were largely clean (free from viral RNA) in this regard, indicating efficient treatment practices at STP. The study, which covered about 80% of the STPs in Hyderabad, revealed that there are around 2 lakh people who are shedding viral materials.
Since only 40% of the Hyderabad sewage reaches STPs, this data can be used to extrapolate the overall number of potentially infected people, which turned out to be approximately 6.6 lakhs, that is, around 6.6% of the city’s population, which includes symptomatic, asymptomatic, and also recently recovered individuals in a time window of about 35 days.