Wastewater Surveillance Sampling for SARS-CoV-2 RNA –‘Testing’ the Waters
By: Laurel Seus, Remediation Microbiologist
As the world continues to monitor COVID-19, the new application of wastewater stream analysis has provided an avenue for monitoring the patterns and trends of communities as we coordinate and evolve our response to the virus. Wastewater surveillance data are intended to complement other COVID-19 surveillance indicators that inform public health actions.
Initiated by the Centers for Disease Control and Prevention (CDC), the Wastewater Surveillance Sampling Strategy allows wastewater streams from individual buildings, combined sewer lines, or wastewater treatment plants to be tested for the presence RNA (ribonucleic acid) from SARS-CoV-2 (the virus that causes COVID-19) to determine if anyone living or working in the area has an active COVID-19 infection. During this process, wastewater samples are concentrated, RNA is extracted, and RT-qPCR (reverse transcription-quantitative polymerase chain reaction) or RT-ddPCR (RT-droplet digital PCR) is used to detect and quantify SARS-CoV-2 RNA from a location.
By using this technology, the CDC is able to provide COVID-19 infection surveillance without having to test every healthy individual on a regular basis regardless of illness symptoms. It may be especially valuable for communities with limited healthcare resources or transportation access where vaccines and testing are limited or not easily accessible. For example, if the wastewater outflow from a nursing home tests positive for SARS-CoV-2 RNA but no residents or staff are symptomatic, quarantine measures can be emplaced until individuals can be tested. Most notably, wastewater surveillance can detect the virus before clinical symptoms and in asymptomatic infections. This testing can also be valuable in the near future for reopening and safety of schools where, as of now, children under age 16 cannot receive the COVID-19 vaccine. Individual testing could then identify an asymptomatic or mild case that may have otherwise become an unknown source of infection within the facility.
This approach to testing wastewater is a “lemons to lemonade” technology from microbiology in the time of COVID-19. It provides proof that environmental microbiology can extend far beyond the environmental sector – intersecting with clinical microbiology and public health. As we vaccinate the general population and the COVID-19 pandemic wanes, the disease will continue to circulate, testing will be less widespread, and the virus is unlikely to be totally eradicated. Wastewater monitoring can help public health officials evaluate the extent of community infections and trends over time as a metric in addition to testing individuals. This technology can be applied to broader wastewater samples, such as wastewater treatment plants or individual sewer lines, that can alert public health officials to an emerging outbreak or be used to monitor the baseline number of cases of the disease.
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