Sewage surveillance: China is tracking its citizens' trash to fight COVID-19

Amid rising COVID-19 infections and crumbling healthcare infrastructure in China, authorities have decided to monitor wastewater as an early warning system. The technique, also known as “sewage surveillance”, appeared on China’s national COVID-19 directives for the first time. 

This technique has already been piloted in Shenzhen and the capital city of Beijing. The task force of the Chinese cabinet has directed the local governments to test water from households flowing into water treatment plants. Local governments are tasked to track changes in positive case rates and viral loads and conduct genome sequencing as part of efforts to mitigate the coronavirus crisis. 

While previous sewage surveillance exercises were focused on evaluating the scale of outbreaks, the task force’s latest directive stated authorities are also required to monitor any variations in virus genomic sequence for identifying potential variants. 

This data would be indicative of community infection levels and distribution of variants of concern, South China Morning Post reported. Experts believe sewage water data can indicate infections earlier than clinical data, allowing healthcare and surveillance workers to enable a more targeted response. 

Principal researcher focusing on wastewater-based epidemiology at the US-based research institute Mathematica Aparna Keshaviah noted sewage surveillance data was one way of ascertaining a rise or decline in infections before community testing was made mandatory and self-reporting systems came into place. 

Janelle Thompson, associate professor of water quality and extremophile biotechnology at Singapore’s Nanyang Technological University stated, “If new variants emerge with heightened risk profiles, wastewater can allow surveillance [workers] to zero in on the dynamics and distribution of that particular variant of concern, enabling a more targeted public health response.”

Elaborating on how the system of monitoring wastewater is of help, Keshaviah mentioned that sewage testing provides officials feedback on whether containment policies are working or not.

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