In a new effort to help mitigate the spread of COVID-19, a network across Ohio is studying samples of wastewater to look for the presence of gene copies/fragments of the virus that causes the disease.
The initiative is a collaboration between the Ohio Department of Health (ODH), the Ohio Environmental Protection Agency (Ohio EPA), the U.S. Environmental Protection Agency (U.S. EPA), the Ohio Water Resources Center (Ohio WRC) at The Ohio State University, and other participating universities, including The University of Toledo, Kent State University, and The University of Akron.
“The system will provide us with early warning signs of possible COVID-19 cases increase in an given community where that testing is being done,” Governor Mike DeWine said during Thursday’s coronavirus briefing. “It will also allow decision makers to move quickly to implement a plan to deal with it.”
As the network expands, sampling and analysis will include other universities with laboratory capabilities.
The increase of COVID-19 cases in communities is typically tracked by testing people with symptoms, an indicator that lags behind the actual spread of the disease.
Because of this, there is a need to use early monitoring methods that estimate the disease’s impact on the broader community.
Research in the U.S. and elsewhere has shown that non-infectious RNA (ribonucleic acid) from the virus that causes COVID-19 (called SARS-CoV-2) can be excreted in the feces of both symptomatic and asymptomatic infected people and can be detected in wastewater as many as three to seven days before those infections lead to increases in case counts or hospitalizations.
As such, monitoring raw wastewater in sewage collection systems can provide an early warning of disease increase in a community.
Community and public health leaders can use this early warning information to make decisions about protective actions to help limit further spread of the disease before cases begin to occur.
The sewage monitoring network will analyze wastewater samples for coronavirus RNA gene copies or fragments at key locations around the state. The network will be expanded over the next few months to include additional wastewater collection sites.
Wastewater entering treatment plants is sampled for fragments of the virus RNA. The wastewater comes from homes in the treatment plant service areas and travels through pipes to the plant.
A mixed wastewater sample (24-hour composite) is collected in an area where all the sewage from a service area enters the plant. This sample is analyzed by a laboratory to determine the number of virus gene copies present, related to the wastewater flow that occurred on the sample day and the population that contributed to the flow.
Based on current research, these virus fragments are not infectious at this sample collection point. It is important to note that the water discharged from the treatment plants is treated to remove viruses and bacteria and is monitored to meet all state and federal discharge limits.
According to the Ohio Department of Health, there are several factors to consider when interpreting viral data in wastewater.
Because scientists are still learning about the timing and rate of shedding of the virus RNA in feces of infected people, it is only appropriate to monitor and observe the trends of viral gene copies detected in a community over time. The data presented in the graphs shows the total number of RNA copies detected in the area from which the wastewater was collected.
A significant increase in viral gene copies over time is an indicator that cases may be increasing in the community. Because infected individuals can continue to shed the virus RNA in feces for 20 to 30 days after they are no longer infectious, decreases in the number of viral gene copies in wastewater might lag behind decreases in cases in a community.
Trends in viral gene copies should be considered along with community case numbers and other COVID-19-related data to inform decisions about taking actions to help limit disease spread.
Sampling sites are being selected to include the monitoring of large, medium, and smaller cities, with a smaller set of sites targeted at Census tracts with vulnerable populations.
Group 1 sample site selection will begin with the seven largest cities in Ohio — Columbus, Cincinnati, Cleveland, Dayton, Akron, Toledo, and Youngstown — to cover the largest percentage of Ohio residents potentially exposed.
Small and medium sized communities have been identified (Group 2) and, depending on remaining sampling capacity, will be prioritized based on Ohio Public Health Advisory System alert levels and data trends, the Ohio vulnerability index, and the availability/willingness of the city to participate in the sampling effort.