Tools for interpretation of wastewater SARS-CoV-2 temporal and spatial trends demonstrated with data collected in the San Francisco Bay Area

• Published in: Water research X Vol. 12; p. 100111
• Main Authors: Greenwald, Hannah D., Kennedy, Lauren C., Hinkle, Adrian, Whitney, Oscar N., Fan, Vinson B., Crits-Christoph, Alexander, Harris-Lovett, Sasha, Flamholz, Avi I., Al-Shayeb, Basem, Liao, Lauren D., Beyers, Matt, Brown, Daniel, Chakrabarti, Alicia R., Dow, Jason, Frost, Dan, Koekemoer, Mark, Lynch, Chris, Sarkar, Payal, White, Eileen, Kantor, Rose, Nelson, Kara L.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2021; Elsevier
• Subjects: Bacteroides; COVID-19; CrAssphage; Human 18S rRNA; Pepper mild mottle virus; Review; Wastewater-based epidemiology; COVID-19; Human 18S rRNA; Pepper mild mottle virus; CrAssphage; Wastewater-based epidemiology; Bacteroides
• ISSN: 2589-9147; 2589-9147
• DOI: 10.1016/j.wroa.2021.100111

•WBE was evaluated at sewershed and facility scales as a pandemic-response strategy.•Wastewater SARS-CoV-2 N1 significantly correlated with COVID-19 cases in aggregate but had locational dependencies.•CrAssphage outperformed PMMoV, Bacteroides, and 18S but normalization did not strengthen correlation to cases.•The apparent WBE case detection limit was estimated as 2.4 COVID-19 new daily cases in 100,000 people.•Early warning provided by WBE depended on location and testing turnaround time. Wastewater surveillance for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA can be integrated with COVID-19 case data to inform timely pandemic response. However, more research is needed to apply and develop systematic methods to interpret the true SARS-CoV-2 signal from noise introduced in wastewater samples (e.g., from sewer conditions, sampling and extraction methods, etc.). In this study, raw wastewater was collected weekly from five sewersheds and one residential facility. The concentrations of SARS-CoV-2 in wastewater samples were compared to geocoded COVID-19 clinical testing data. SARS-CoV-2 was reliably detected (95% positivity) in frozen wastewater samples when reported daily new COVID-19 cases were 2.4 or more per 100,000 people. To adjust for variation in sample fecal content, four normalization biomarkers were evaluated: crAssphage, pepper mild mottle virus, Bacteroides ribosomal RNA (rRNA), and human 18S rRNA. Of these, crAssphage displayed the least spatial and temporal variability. Both unnormalized SARS-CoV-2 RNA signal and signal normalized to crAssphage had positive and significant correlation with clinical testing data (Kendall's Tau-b (τ)=0.43 and 0.38, respectively), but no normalization biomarker strengthened the correlation with clinical testing data. Locational dependencies and the date associated with testing data impacted the lead time of wastewater for clinical trends, and no lead time was observed when the sample collection date (versus the result date) was used for both wastewater and clinical testing data. This study supports that trends in wastewater surveillance data reflect trends in COVID-19 disease occurrence and presents tools that could be applied to make wastewater signal more interpretable and comparable across studies. [Display omitted]