A recent study from Southern California demonstrated the efficiency of using wastewater-based epidemiology (WBE) as an alternative viral detection method to fight against Covid-19. WBE quantifies the abundance and genetic diversity of SARS-CoV-2, amongst other viral pathogens, by examining influent samples from municipal wastewater treatment plants. These studies present a promising outlook on the potential of WBE to act as an early warning system to predict subsequent Covid-19 outbreaks, mutations, and infection rates accurately.
The 2021 study by Rothman and researchers from the University of California, Irvine, published in Applied and Environmental Microbiology, detailed the findings from 94 influent samples they collected over six months from seven wastewater treatment plants (WTPs) across Southern California. Out of the samples collected from Los Angeles, Orange, and San Diego counties, 85 samples were subjected to metatranscriptomic sequencing; copies of the SARS-CoV-2 N1 gene were quantified per litre of wastewater and compared against county case numbers. Overall, the SARS-CoV-2 viral load in WTPs correlated with the seven-day rolling average of countywide Covid-19 cases. California has experienced fluctuations in new Covid-19 cases since the start of the pandemic in 2020 (Figure 1). If WBE is implemented as a tool to inspect SARS-CoV-2 contamination levels routinely across the US, it could provide public health authorities with a good level of predictive analysis to inform decision-making to prevent a surge in Covid-19 cases.
WBE utilises the collective human waste from a given community; it can detect otherwise undiagnosed positive cases from the asymptomatic population without invasive nose swabs that rely on individual compliance. A reliable detection system can allow earlier mobilization of Covid-19 resources ahead of an outbreak and thus reduce hospital admissions, which will help decrease pressure on already-strained healthcare systems. The understanding of WBE and its abilities can be deepened with continued research in this field. Covid-19 is an economic and health burden that continues to impact many countries around the world negatively. WBE has the potential to develop into a valuable tool that governments can use to prevent future outbreaks and further understanding of SARS-CoV-2 mutation over time and across different regions and populations.