hidden COVID surge – Wastewater surveillance in Bengaluru closely tracked COVID-19 trends during the first Omicron wave, but later emerged as a key tool in identifying hidden surges that were not fully caught through routine diagnostic testing, according to researchers who studied the city’s sewage-based surveillance network. A study published in PLOS Global Public Health by researchers from the Indian Institute of Science (IISc), the International Center for Theoretical Sciences (ICTS) which is a part of the Tata Institute of Fundamental Research (TIFR) and the Tata Institute for Genetics and Society (TIGS) found that wastewater surveillance mirrored the increase in COVID-19 cases during the Omicron wave, although it did not give early warning of the increase. The researchers said that viral loads detected in sewage and reported infections increased almost simultaneously during that phase, limiting its usefulness as a predictive tool.

However, subsequent wastewater surveillance indicated that as diagnostic testing declined in the later stages of the pandemic, sewage surveillance became increasingly valuable in identifying fresh waves of infection that might otherwise have been underreported.