A team of researchers led by North Carolina State University compared wastewater monitoring and two other COVID-19 surveillance approaches in Raleigh, N.C., during the start of the pandemic. They found that wastewater and syndromic surveillance monitoring are useful complements to lab-confirmed case surveillance.
From April through December 2020, the research team developed methods and analyzed two measures of wastewater (raw wastewater and solids settled from wastewater) for SARS-CoV-2 RNA in samples from the Raleigh, N.C., wastewater treatment plant. They compared wastewater results with lab-confirmed COVID-19 cases and cases of COVID-like illness – or syndromic cases not confirmed through laboratory testing – to determine whether and/or when the data sets correlated, as well as whether periods of increasing or decreasing trends aligned across the data sets.
“The overall purpose was to look across four different data sets in one geographic area and see how they were in agreement,” says Nadine Kotlarz, a research scholar in NC State’s Department of Biological Sciences and co-corresponding author of a paper describing the work.
“Each surveillance approach has its unique strengths and limitations. We weren’t attempting to determine which surveillance method was best; rather, we wanted to create a holistic picture of how the various tools at a health department’s disposal might work together to help them get a handle on a pandemic.”
The research team applied standard correlation and linear regression analyses across datasets to evaluate when the different surveillance approaches agreed with one another, and whether some approaches provided an earlier warning of changing trends.
The greatest correlation between data sets was between lab-confirmed and syndromic cases. However, SARS-CoV-2 RNA concentrations in wastewater influent and solids were also highly correlated with both lab-confirmed cases and syndromic cases.
“All four metrics showed sustained increases in COVID-19 in June, July, and November 2020, and sustained decreases in August and September 2020,” Kotlarz says. “In the Raleigh system, lab-confirmed cases and wastewater influent were earlier indicators of change, followed by syndromic cases and wastewater solids.”
“I think this work is important because it could allow public health officials to understand their data better,” says Francis de los Reyes III, professor of civil, construction and environmental engineering at NC State and paper coauthor. “Particularly when you’re in a situation where clinical testing is low, being able to look at all the data in one place can help officials get a handle on what’s happening.”
“While wastewater monitoring isn’t a solo strategy for numerous reasons – not everyone is connected to a sewer, for example – knowing that wastewater and syndromic COVID-19 case surveillance complement lab-confirmed case surveillance, especially at the beginning of a pandemic, supports their use as a valuable tools in tracking COVID-19 infection dynamics,” says Angela Harris, assistant professor of civil, construction and environmental engineering at NC State and co-corresponding author of the research.”
The work appears in the American Journal of Public Health and was supported by the National Science Foundation (Rapid Response Research grant CBET- 2029025), the North Carolina Policy Collaboratory, and North Carolina State Center for Human Health and the Environment (grant P30ES025128). David Holcomb and Lawrence Engel from the University of North Carolina at Chapel Hill, as well as Virginia Guidry, Ariel Christensen and Steven Berkowitz from the North Carolina Department of Human Health and Services, also contributed to the work, which was done in partnership with the Neuse River Resource Recovery Facility.
Note to editors: An abstract follows.
“Timing and trends for municipal wastewater, lab-confirmed case, and syndromic case surveillance of COVID-19 in Raleigh, North Carolina, USA”
Authors: Nadine Kotlarz, Tanvir Pasha, Stacie Reckling, Judith Kays, Yi-Chun Lai, Sean Daly, Sivaranjani Palani, Jane A. Hoppin, Helena Mitasova, Francis L. de los Reyes III, Angela Harris, North Carolina State University; David A. Holcomb, Lawrence S. Engel, University of North Carolina Chapel Hill; Erika Bailey, Raleigh Water, Raleigh, N.C.; Virginia T. Guidry, Ariel Christensen, Steven Berkowitz, North Carolina Department of Health and Human Services
Published: Nov. 10, 2022 in the American Journal of Public Health
Objectives. To compare 4 COVID-19 surveillance metrics in a major metropolitan area.
Methods. We analyzed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater influent and primary solids in Raleigh, North Carolina, from April 10 through December 13, 2020. We compared wastewater results with lab-confirmed COVID-19 cases and syndromic COVID-like illness (CLI) cases to answer 3 questions: (1) Did they correlate? (2) What was the temporal alignment of the different surveillance systems? (3) Did periods of significant change (i.e., trends) align?
Results. In the Raleigh sewershed, wastewater influent, wastewater primary solids, lab-confirmed cases, and CLI were strongly or moderately correlated. Trends in lab-confirmed cases and wastewater influent were observed earlier, followed by CLI and wastewater primary solids. All 4 metrics showed sustained increases in COVID-19 in June, July, and November 2020 and sustained decreases in August and September 2020.
Conclusions. In a major metropolitan area in 2020, the timing of and trends in municipal wastewater, lab-confirmed case, and syndromic case surveillance of COVID-19 were in general agreement.
Public Health Implications. Our results provide evidence for investment in SARS-CoV-2 wastewater and CLI surveillance to complement information provided through lab-confirmed cases.
This post was originally published in NC State News.