What is your current limit of detection (LOD)?
Our current protocol has a limit of detection of 9,000 SARS-CoV-2 virus copies per liter of wastewater. We reliably detect the virus when there is at least 1 infected person in a population of 6,500 people. In other words, our methods are sensitive enough to detect even 1 infected person in a community of 6,500 people or smaller.
How should I calculate the change since my last sample or plot my own data?
If you are interested in plotting the data yourself or conducting additional analyses, we highly recommend using the effective concentration measurement. We have found that normalizing the data to a virus universally found in stool is the best way to control for dilution, variability in sampling, and changes in lab protocol. To interpret patterns in your community, we recommend looking at consistent trends across multiple samples, rather than sample-to-sample changes.
How well does your data reflect COVID-19 cases?
Since the start of the pandemic, our dataset showed a consistent correlation between wastewater concentrations and confirmed new COVID-19 cases reported on state and even county levels. For example, our sampling locations' wastewater data accurately reflected both localized peaks in COVID-19 cases last summer (2020), as well as the nationwide surges in late fall 2020. As Omicron became the dominant variant in late 2021 and early 2022, case counts were underreported, and Biobot’s data showed much higher levels of COVID-19 than reported cases. This pattern suggests that rather than correlating directly with clinical case counts, wastewater epidemiological data can instead be a strong indicator of the true number of infections, reported or otherwise.
What contributes to the variability in the data?
The variability of wastewater data depends on many factors, including lab processing, catchment population size, and sampling differences.
We are continuously reviewing and improving our lab processes to ensure high-quality data. At the same time, one of the most important factors to improve data quality is the pumping frequency. Therefore, if your data is highly variable, we recommend increasing your pumping frequency to the maximum setting (e.g. pumping every 5 minutes) to mitigate any potential variability from the non-continuous nature of composite sampling.
Do the mRNA vaccines affect our measurement of the virus in wastewater?
No. At this time, vaccines do not affect the amount of virus detected in wastewater samples.
For more information, please visit: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html