Quantifying the relationship between SARS-CoV-2 wastewater concentrations and building-level COVID-19 prevalence at an isolation residence using a passive sampling approach

Abstract

SARS-CoV-2 RNA can be detected in the excreta of individuals with COVID-19 and has demonstrated a positive correlation with various clinical parameters. Consequently, wastewater-based epidemiology (WBE) approaches have been implemented globally as a public health surveillance tool to monitor the community-level prevalence of infections. Over 270 higher education campuses monitor wastewater for SARS-CoV-2, with most gathering either composite samples via automatic samplers (autosamplers) or grab samples. However, autosamplers are expensive and challenging to manage with seasonal variability, while grab samples are particularly susceptible to temporal variation when sampling sewage directly from complex matrices outside residential buildings. Prior studies have demonstrated encouraging results utilizing passive sampling swabs. Such methods can offer affordable, practical, and scalable alternatives to traditional methods while maintaining a reproducible SARS-CoV-2 signal. In this regard, we deployed tampons as passive samplers outside of a COVID-19 isolation unit (a segregated residence hall) at a university campus from February 1, 2021 - May 21, 2021. Samples were collected several times weekly and remained within the sewer for a minimum of 24 hours (n = 64). SARS-CoV-2 RNA was quantified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) targeting the viral N1 and N2 gene fragments. We quantified the mean viral load captured per individual and the association between the daily viral load and total persons, adjusting for covariates using multivariable models to provide a baseline estimate of viral shedding. Samples were processed through two distinct laboratory pipelines on campus, yielding highly correlated N2 concentrations. Data obtained here highlight the success of passive sampling utilizing tampons to capture SARS-CoV-2 in wastewater coming from a COVID-19 isolation residence, indicating that this method can help inform public health responses in a range of settings.

Effectiveness of passive sampling for the detection and genetic characterization of human viruses in wastewater

“…20 Since the beginning of the COVID-19 pandemics, passive samplers have been proposed as affordable and easy-to-use alternative for virus surveillance in small scale scenarios. 8…”

“…7 Passive samplers have thus been proposed as affordable and easy-to-use alternative for virus surveillance in these smaller scale scenarios. 8 Their deployment and further collection are easy and fast, they operate without electricity, so they can be used in any point of the sewer system.…”

“…20 Since the beginning of the COVID-19 pandemics, passive samplers have been proposed as affordable and easy-to-use alternative for virus surveillance in small scale scenarios. 8 Next generation sequencing (NGS) techniques are excellent tools to monitor and identify viral pathogens circulating among the population. Sewage contains a high number of viruses and viral metagenomics (i.e., viromics) is a very promising tool that could be paired to WBE for a more complete description of viruses circulating within a population as well as for the study of viral (re)emergences and discovery.…”