Researchers used a recently developed method of wastewater genomic surveillance to detect SARS-CoV-2 infections on the University of California, San Diego (UCSD), campus during 10 months of the pandemic. The approach identified viral variants of concern as early as 2 weeks before the variants showed up in clinical tests, the team recently reported in Nature.

Why This Is Important

Most people with current or recent SARS-CoV-2 infections shed the virus RNA in their stool, regardless of whether they’re symptomatic, and fragments of this RNA are detectable in wastewater samples.

Monitoring wastewater provides an efficient snapshot of the types and amounts of viruses and bacteria spreading in a community, which can augment data from clinical tests. A single wastewater sample gives a substantial amount of information about an entire building, town, or county, making it cost-effective. “[Y]ou would have to sequence a ton of clinical or nasal swabs to get that level of resolution,” Smruthi Karthikeyan, PhD, MS, a UCSD postdoctoral scholar and lead author of the recent study, said in an interview with JAMA.

The new study suggests that, in addition to tracking SARS-CoV-2 transmission levels, wastewater surveillance also could be used to detect emerging viral variants when they first appear in an area.

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