UC Davis: New Equipment Increases Capabilities for Early Detection

Healthy Davis Together wastewater monitoring operations, led by UC Davis researchers with support from the city’s Department of Public Works, has deployed newly arrived wastewater sampling equipment to 15 additional sample collection locations (nodes), expanding monitoring to more neighborhoods served by the city wastewater collection system. The virus that causes COVID-19 (SARS-CoV-2) can be shed in the stool of infected individuals, including individuals who do not yet have symptoms or who never have symptoms. Regular testing of wastewater can detect spikes and be used as an early warning detection system so that action can be directed to individual testing efforts that help prevent spread.

“Davis is one of few cities to have a full-scale environmental monitoring program in place,” said Heather Bischel, project lead for wastewater monitoring for Healthy Davis Together and assistant professor in UC Davis’ Department of Civil and Environmental Engineering. “Recent low levels in wastewater confirm what we see with our low positivity rate. An elevated reading could mean there are asymptomatic infections that haven’t been identified yet, or that virus is being shed by individuals already properly in quarantine and receiving care. Either way, it’s important for residents to be kept informed so they can take appropriate action to stay well.”

While Davis has maintained a low positivity rate of 1% or less for the past two months, Healthy Davis Together community COVID-19 testing continues to identify positive cases. Wastewater analysis remains an important detection and prevention tool. Elevations in virus levels serve as an important reminder to remain vigilant, follow public health guidelines and continue to get tested for COVID-19, even after getting vaccinated. Since Healthy Davis Together started monitoring wastewater last November, the COVID-19 virus has been detected in city wastewater — that is normal and expected until there is no longer COVID-19 in Davis.

Healthy Davis Together wastewater testing looks for data changes over time. Samples are collected from throughout the sewer system twice a week and analyzed in Bischel’s lab. These data and data from the city’s wastewater treatment plant, which is monitored daily, are viewed together to determine if the presence of the virus is going up, going down or staying the same. These findings are updated and shared on the Healthy Davis Together website every Saturday. Beginning in April, community members who have registered to receive community messages through the Yolo Alert system will receive important wastewater updates. The city will also post important information on wastewater virus levels to neighborhoods via Nextdoor.

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