How do Biobot's community wastewater tiers relate to other pandemic metrics?
Biobot compared how frequently data in each tier corresponded with each CDC Community Transmission Level from June 2020 to October 2021. We chose this metric because it was the gold standard for community transmission rates at the time. We chose this timeframe because it was during a time period of relatively high case reporting and prior to the widespread adoption of at-home testing.
Our analysis showed consistent alignment between Biobot’s tiers and CDC Transmission Levels. The highest COVID-19 wastewater tier correlated especially closely with the High CDC Community Transmission Level across all catchment area sizes. This means that if wastewater data were in Tier 4, the vast majority of sampling locations were also in a High CDC Transmission Level at that time.
How do Biobot's community wastewater tiers relate to other pandemic metrics?
Biobot and others have shown that wastewater concentrations correlate to cases. Even as case ascertainment changes, we expect wastewater data to remain reflective of COVID-19 activity in a community. However, Biobot’s community wastewater tiers are not intended to provide estimates of numbers of cases in a population; we suggest using the tiers to estimate relative COVID-19 activity in the community.
Will the tiers change as the pandemic changes?
Regardless of how the pandemic changes, Biobot’s community tiers provide context for COVID-19 activity in the community. Keeping the tiers the same allows for comparability across time. For example, analyzing changes in the proportion of sampling locations in Tier 4 can provide insight into shifts in community COVID-19 activity.