COVID-19 Testing in Sewage

The Science

Early into the COVID-19 pandemic doctors reported finding RNA fragments of the COVID-19-causing SARS-CoV-2 virus in the stool of symptomatic patients. Soon after a study conducted in the Netherlands was the first to detect fragments of the virus in sewage¹.

At that time, COVID testing of individual patients could not keep up with demand, thus monitoring SARS-CoV-2 in wastewater presented the alternative of testing infection rates community-wide. This spurred an unseen number of scientific studies that assessed the applicability of wastewater monitoring including validating primer sets, optimizing concentration methods, and refining analytic steps.

The results are clear: SARS-CoV-2 testing in wastewater can indicate community-wide infections days before increases in Covid cases are reported. In the current state of the pandemic, this opens several use cases².

Use Cases

Because SARS-CoV-2 (the virus that causes COVID-19) RNA fragments can be detectable in sewage about a week before people even show symptoms the continuous monitoring of SARS-CoV-2 can serve as an early warning system for public health authorities.

In August, at the University of Arizona wastewater testing informed about the presence of the coronavirus in a dorm, resulting in identifying two asymptomatic students. This method has also helped identify positive cases at the University of Virginia, the Rochester Institute of Technology, the Colorado State University, and many other universities since then.

The same approach is beneficial for nursing homes, correctional facilities, and other aggregated living facilities where regular testing of individuals is either not feasible or too costly.

Regular environmental surveillance can be used as a way to determine whether COVID-19 has truly been contained in an area and/or as an additional source of information that supports decision-making about whether to adjust public health and social measures.

The CDC is currently developing a portal for state, tribal, local, and territorial health departments to submit wastewater testing data into a national database for use in summarizing and interpreting data for public health action. Participation in a national database will ensure data comparability across jurisdictions and benefit every participant.

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References:
¹Medema, G., Heijnen, L., Elsinga, G., Italiaander, R. and Brouwer, A., 2020. Presence of SARS-Coronavirus-2 in sewage. MedRxiv.
²WHO Status of environmental surveillance for SARS-CoV-2 virus, Scientific Brief, 7 August 2020