What Is the Ohio Coronavirus Wastewater Monitoring Network?
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. As the network expands, sampling and analysis will include other universities with laboratory capabilities.
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Why Is This Being Done?
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.
Where Is This Being Done?
The sewage monitoring network will analyze wastewater samples for coronavirus RNA gene copies or fragments at key locations around the state. (Sample collection sites are shown on the map below.) The network will be expanded over the next few months to include additional wastewater collection sites.
How Does It Work?
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.
Where Can I Find Results?
Click on a dot on the map to see the location of a collection site and obtain information on the viral gene copies detected in that location. When available from the utility, the area displayed in light blue on the map shows the geographic boundaries of the service area collected by the sewer system that was sampled. The data will be updated at 2 p.m. on days when the Ohio Department of Health receives information from sampling sites. Currently that information is reported to the Ohio Department of Health two to three times per week, but as the network and sampling capacity expands the data will be updated daily.
What Do the Results Mean?
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. (See “What Is Shown on the Viral Gene Copy Trend Graph?” below for more details.) 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.
How Will the Ohio Wastewater Monitoring Network Improve Public Health?
The network will:
- Serve as an early warning of infection in communities or congregate settings.
- Provide information that can help local communities more quickly intervene with protective measures to slow disease spread.
- Help communities measure the effectiveness of such interventions (quarantine/face coverings/business limitations).
- Develop methodologies/predictive models to translate viral loads detected for comparison with other data, such as rates or percentage of infection in communities.
- Where possible, compare results to previously collected data on prevalence in specific communities to better understand factors affecting disease spread.
- Determine impacts on disproportionately affected communities or communities where risk of infection is greater.
Where Can I Find More Information on the Ohio Wastewater Monitoring Network?
Additional Technical Information
What Are the Objectives of the Ohio Coronavirus Wastewater Monitoring Network?
The Ohio Water Resources Center at The Ohio State University will:
- Coordinate a network of state university labs, in addition to the U.S. EPA, to analyze wastewater for virus gene copies at locations across the state.
- In coordination with the U.S. EPA and the Centers for Disease Control and Prevention (CDC), develop a set of standardized methods and procedures for sampling and analyzing at wastewater treatment plants and specific locations in the plant service areas to ensure consistent and accurate comparison of results obtained from the laboratory network.
- Help with coordination and data sharing with other organizations collecting similar wastewater data (i.e., Biobot, Battelle, Stanford University) to ensure all data collected in Ohio is available to inform decisions.
- Establish management and collection of the data from the university networks and U.S. EPA into one database for upload to the Innovate Ohio Platform.
- In coordination with ODH and Ohio EPA, identify and develop a prioritization process for selecting the next group of sites to add to the network using the Ohio Health Advisory System and community vulnerability data related to issues such as higher populations, increased disease burden, health disparities, and congregate settings.
- Display viral gene copy trends (at all sampling locations via graphs/charts on the coronavirus.ohio.gov website) that can help state agencies and local communities implement appropriate intervention actions (such as closing certain facilities) to help prevent spread of the virus.
- Evaluate current models that can use the raw viral load data to make predictions on the likely percentage of people infected in the area the sewage came from. (Project researchers are collaborating with the CDC and U.S. EPA on model development with projected model results by fall 2020.)
How Are Sampling Sites Selected?
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.
What Is Shown on the Viral Gene Copy Trend Graph?
Infected individuals shed the virus RNA in their feces at different rates based on the severity and timing of their infections, and wastewater flowing from homes with infected individuals can change during the course of a day. In addition, the amount of flow received at a wastewater treatment plant on any given day can change based on water use in a community, the age of the system, and other factors. Because of these factors, the number of gene copies detected at each sampling location is multiplied by the average flow on the sampling day. (This is referred to as “normalizing” the viral gene copy results.) Four samples are analyzed from each sampling site, and the data is presented as the geometric mean (a way scientists determine the average value of this type of data) of those samples.
When reviewing the sampling results, it is most important to evaluate the trend in viral gene copies. A 10-times, 100-times, or higher increase is more significant than an actual increase in the number value. For example, an increase from 600 to 5,000 gene copies (a nearly 10-times increase) is more significant than an increase from 1,200 to 3,000 viral gene copies. Because each community has different populations and different wastewater flow volumes, it is not appropriate to compare actual viral gene copy numbers between communities, but reviewing the trend in a specific community can be used to help understand whether cases or hospitalizations are likely to increase.
Sewershed Monitoring for RNA From SARS-CoV-2
A sewershed is an area of land where the raw sewage from homes, businesses, and industries flows through a series of pipes to a single downstream point, where it enters a wastewater treatment plant. Samples of the raw wastewater can be collected and monitored for the virus’s RNA before going through treatment. Additional data collected at this point helps researchers evaluate the strength and nature of the wastewater to allow for proper analysis of the RNA fragments. Before being discharged from the treatment plants, wastewater is treated to remove viruses and bacteria and is monitored to meet all state and federal discharge limits.
Protocols and Standards for Wastewater Sampling for SARS-CoV-2 RNA
The development and use of standard protocols and methods for sampling and analyzing the waste are important to ensure the sample results are correct. The Ohio Water Resources Center and participating university researchers are closely collaborating with the U.S. EPA, CDC, and ODH to develop standard methods for wastewater sample collection, processing the waste to prepare it for laboratory analysis, analysis of the waste, verification of results, and reporting of the data. More information on these standard protocols and methods can be found at https://wrc.osu.edu/.