Graph showing the level of Covid, Influenza and RSV in wastewater systems in the United States, by city

How to interpret these data?

Rather than looking at a data point, we recommend tracking trends over time. Our analysis suggests that SARS-CoV-2 gene concentrations are strongly correlated with sewer COVID-19 incidence rates [read the research].

How to read these results?

Results can be filtered by location to show the presence of SARS-CoV-2 RNA in wastewater. Each location includes the copies of SARS-CoV-2 per gram of dry solid waste and the copies per gram of the Omicron variant.

Table and graph data have been smoothed, where measurements from nearby dates have been combined to reduce daily variability and increase accuracy. Specifically, we take the 5 samples centered around a date and report the mean after excluding the highest and lowest values. This processing minimizes the influence of outliers and facilitates the visualization of trends in the data.

If the target is not detected in the sample, the concentration is reported as 0 c/g. There may still be very small amounts of the target present that are below the detection limits of our procedure. When a sample was not tested for a target, the concentration for that target is reported as "-".

Learn more about variability in wastewater data.

Please see the data dictionary for more information on each column displayed in table view.

What does "copies per gram" mean?

Results reported as copies of SARS-CoV-2 per gram (dry weight) of wastewater solids tell you how many copies of the SARS-CoV-2 virus were found in one gram of solid waste from one location. This data point can be used as an indicator of the number of people in a sewer basin (the geographic area served by a particular sewage treatment plant) who have COVID-19. Over time, you will see this value increase and decrease, indicating more or less clinical cases of COVID-19 in the population served by treatment plants.

What is PMMoV normalization?

In addition to the pathogens it tests for, WastewaterSCAN measures an extremely common and harmless plant virus that is consumed when people eat. This is the mild pepper mottle virus (or PMMoV). By measuring the concentration of PMMoV genetic markers per gram dry weight of wastewater solids, WastewaterSCAN can account for the amount of viral material recovered from each sample and changes in that sample's 'faecal strength'. For example, heavy rain flowing into a sewage system can dilute the strength of a particular day's sample. This approach allows day-to-day results to be compared.

Our analysis suggests that SARS-CoV-2 gene concentrations measured in copies per gram of solid waste and PMMoV-normalized concentrations are proportional to those confirmed in laboratory Incidence rate of COVID-19 in sewers. Moreover, the relationship between these wastewater measurements and COVID-19 incidence rates is consistent across the sewage basins in this study. This means that a higher sewage value in one factory compared to another suggests that the incidence rates of COVID-19 are higher in the sewage basin of that factory compared to others. The references

MSYSTEMS