Focus is now on sewage surveillance to detect emerging variants

The sewage treatment plant at Doddabele. Top health officials in the State have confirmed the presence of BA.4 and BA.5 sub-lineages of Omicron in wastewater samples.

The sewage treatment plant at Doddabele. Top health officials in the State have confirmed the presence of BA.4 and BA.5 sub-lineages of Omicron in wastewater samples. | Photo Credit: File photo

With some samples of sewage surveillance in Bengaluru having shown the presence of “possible” BA.4 and BA.5 sub-lineages of Omicron, there is an increased focus on it now.

While top health officials in the State confirmed the presence of these variants in wastewater samples, they said it is yet to be correlated through genome sequencing.

Sewage surveillance is known to help in early identification of any impending wave of COVID-19 and notifying the emergence of new variants of SARS-CoV 2, if any, to initiate local public health actions. Six agencies are involved in sewage surveillance in Karnataka for the last one year. Last month, the Infectious Disease Research Foundation (IDRF) was granted permission to take up sewage surveillance in select sites in Bengaluru city, Bengaluru international airport and Mangaluru airport. 

Following a recommendation by the State’s COVID-19 Technical Advisory Committee (TAC), the State Health Department on June 7 set up an eight-member sewage surveillance appraisal committee headed by the TAC chairman. The committee has been asked to submit bi-weekly reports to the TAC.

Final certification

State Health Commissioner Randeep D. said areas with a high case load detected in sewage surveillance are being prioritised for COVID testing. “Waste water analysis is an early detection tool to assess the spread of new sub-lineages and variants in a hotspot area of increased positivity. Some samples have shown the presence of possible BA.4 and BA.5 sub-lineages of Omicron in the city. However, the final certification of such detections would be only after confirmation by Indian SARS-CoV -2 Genomics Consortium (INSACOG),” the Commissioner told The Hindu.

TAC chairman M.K. Sudarshan said after the third wave, many people are not coming forward to get tested. “Moreover, there is a restriction on testing asymptomatic persons as per the ICMR’s purposive testing strategy. The testing levels are low due to these reasons, resulting in poor information on emerging variants. Sewage surveillance will provide early warning on an impending local surge of COVID-19 and an estimate of the disease burden in a particular region,” he said.

Pointing out that the first SSAC meeting was held on June 11, Dr. Sudarshan said the committee has representation of all the organisations involved in wastewater surveillance. The IDRF is preparing to start sewage surveillance in the third week of June, he said.

C.N. Manjunath, member of the State’s Clinical Experts Committee, said several studies have demonstrated that increases in SARS-CoV-2 RNA can be detected in environmental samples several days before detection of COVID-19 through clinical surveillance.

Highest in Mahadevapura

Bhaskar Rajakumar, a public health consultant who is part of the TAC and also heads the COVID war room at BBMP, said sewage surveillance has shown a slight surge in positivity rate in Mahadevapura in the last few days.  “Wastewater surveillance has shown a jump from 33% positivity rate in the last week of May to 75% in the first week of June. The current rise in number of cases in Mahadevapura is also indicating the same. This is mainly because Mahadevapura is an IT corridor with a huge migrant population. This has been the trend in all the three previous waves,” Dr. Rajakumar added..

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Printable version | Aug 6, 2022 10:32:55 am | https://www.thehindu.com/news/national/karnataka/focus-is-now-on-sewage-surveillance-to-detect-emerging-variants/article65537638.ece