Passive sampling to scale wastewater surveillance of infectious disease: Lessons learned from COVID-19

Abstract

Much of what is known and theorized concerning passive sampling techniques has been developed considering chemical analytes. Yet, historically, biological analytes, such as Salmonella typhi, have been collected from wastewater via passive sampling with Moore swabs. In response to the COVID-19 pandemic, passive sampling is re-emerging as a promising technique to monitor SARS-CoV-2 RNA in wastewater. Method comparisons and disease surveillance using composite, grab, and passive sampling for SARS-CoV-2 RNA detection have found passive sampling with a variety of materials routinely produced qualitative results superior to grab samples and useful for sub-sewershed surveillance of COVID-19. Among individual studies, SARS-CoV-2 RNA concentrations derived from passive samplers demonstrated heterogeneous correlation with concentrations from paired composite samples ranging from weak (R² = 0.27, 0.31) to moderate (R² = 0.59) to strong (R² = 0.76). Among passive sampler materials, electronegative membranes have shown great promise with linear uptake of SARS-CoV-2 RNA observed for exposure durations of 24 to 48 h and in several cases RNA positivity on par with composite samples. Continuing development of passive sampling methods for the surveillance of infectious diseases via diverse forms of fecal waste should focus on optimizing sampler materials for the efficient uptake and recovery of biological analytes, kit-free extraction, and resource-efficient testing methods capable of rapidly producing qualitative or quantitative data. With such refinements passive sampling could prove to be a fundamental tool for scaling wastewater surveillance of infectious disease, especially among the 1.8 billion persons living in low-resource settings served by non-traditional wastewater collection infrastructure.

Keywords: COVID-19; Environmental surveillance; Moore swab; Passive sampling; SARS-CoV-2; Wastewater surveillance; Wastewater-based epidemiology.

Graphical abstract

Fig. 1

Comparison of the reported SARS-CoV-2 concentrations in wastewater by composite sampling, genome copies per liter (GC/L), with paired passive samples, genome copies per passive sampler processed (GC/passive sampler processed) across five studies. Schang et al. (2021) (dark gray) and Habtewold et al. (2022) (open circles) data were extracted from the published supplemental. Habtewold et al. (2022) compares three different passive sampler types to a paired composite, therefore although nine points are represented, these represent three paired samples. The University of Massachusetts Amherst (UMass, gold), University of Maine (UMaine, red), and University of Connecticut (UConn, blue) datasets (unpublished) were provided by co-authors. Brief descriptions of these sampling campaigns are provided in the Supplemental Information. The concentrations were log transformed, and linear regressions were fit to each series individually (except for Habtewold et al., 2022) and to the aggregated data with the resulting fit and r² shown. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)