Wastewater data revealed hidden COVID surges in Bengaluru after testing declined

Wastewater surveillance in Bengaluru closely tracked COVID-19 trends during the first Omicron wave, but later emerged as an important tool in identifying hidden surges that were not fully captured through routine clinical testing, according to researchers studying the city’s sewage-based monitoring network. 

A study published in PLOS Global Public Health by researchers from the Indian Institute of Science (IISc), International Centre for Theoretical Sciences (ICTS) which is a part of the Tata Institute of Fundamental Research (TIFR) and Tata Institute for Genetics and Society (TIGS) found that wastewater surveillance mirrored the rise in COVID-19 cases during the Omicron wave, though it did not provide an early warning of the surge. Researchers said viral loads detected in sewage and reported infections rose almost simultaneously during that phase, limiting its usefulness as a predictive tool. However, subsequent wastewater monitoring indicated that as clinical testing declined in later phases of the pandemic, sewage surveillance became increasingly valuable in identifying fresh waves of infection that may otherwise have gone underreported.