Table 1.
Overview of case studies including information on wastewater service area, sampling, testing, and clinical case data
| Characteristic | Virginia Beach, VA | San Jose, CA |
|---|---|---|
|
| ||
| Geographic area | Atlantic Treatment Plant, Hampton Roads region, VA, USA | San Jose wastewater treatment plant, Santa Clara County, CA, USA |
| Sewershed population | 343,016 | 1,458,000 |
| Wastewater sampling dates | 6/2/20 to 2/9/21 | 3/18/20 to 3/31/21 |
| Sampling frequency | 1 per week | Weekly from 3/18/20 to 7/14/20, then 5 × /week |
| Wastewater matrix | Primary influent | Primary settled solids |
| Number wastewater samples | 37 | 195 |
| Sample collection | 24-h flow-weighted composite | 24-h composite solids sample |
| Sample concentration | Electronegative membrane filtration with MgCl2 addition and acidification followed by extraction via NucliSENS easyMag. Solids were not removed or allowed to settle prior to filtration. | Dewatering by centrifugation at 24,000 g at 4 °C for 30 min and decanting supernatant. Extraction of 1.8 – 2.8 g of sample using the RNeasy PowerSoil total RNA kit with further purification using Zymo OneStep PCR inhibitor removal columns. |
| SARS-CoV-2 RNA RT-PCR target | N1, N2a | N |
| Detection technology | 1-step RT-ddPCR | 1-step RT-ddPCR |
| Case study reference | Gonzalez et al. (2020, 2021) | Graham et al. (2021); Kim et al. (2022); Wolfe et al. (2021) |
| Case data geographic area | The sewershed area determined from the treatment plant service area polygon and address-level case data | The sewershed service area of the treatment plant comprises approximately 75% of the cumulative cases for the entire county |
| Case data dates | Earliest available data hierarchy: (1) illness onset date; (2) specimen collection date of earliest associated lab; (3) date of diagnosis; (4) earliest date received by local/ county health department, date received by state, date of report, investigations start date, confirmation date, investigation create date | 1/27/2020 to 11/4/2021 reported by Santa Clara County Health District. |
PCR, polymerase chain reaction; ddPCR, digital droplet PCR.
a
In 2021, this changed to using a single N target, a slight modification of the N2 target published by Gonzalez et al. (2020, 2021).