key: cord-0723317-478of6dq
authors: Kapoor, Vikram; Al-Duroobi, Haya; Phan, Duc C.; Palekar, Rakhee S.; Blount, Bobby; Rambhia, Kunal J.
title: Wastewater Surveillance for SARS-CoV-2 to Support Return to Campus: Methodological Considerations and Data Interpretation
date: 2022-04-02
journal: Curr Opin Environ Sci Health
DOI: 10.1016/j.coesh.2022.100362
sha: 5d0b6dd8e8ffd6386d5d612b5e912399435f9c7d
doc_id: 723317
cord_uid: 478of6dq

The COVID-19 pandemic has been challenging for various institutions such as school systems due to widespread closures. As schools re-open their campuses to in-person education, there is a need for frequent screening and monitoring of the virus to ensure the safety of students and staff and to limit risk to the surrounding community. Wastewater surveillance (WWS) of SARS-CoV-2 is a rapid and economical approach to determine the extent of COVID-19 in the community. The focus of this review is on the emergence of WWS as a tool for safe return to school campuses, taking into account methodological considerations such as site selection, sample collection and processing, SARS-CoV-2 quantification, and data interpretation. Recently published studies on the implementation of COVID-19 WWS on school and college campuses were reviewed. While there are several logistical and technical challenges, WWS can be used to inform decision making at the school campus and/or building level.

The COVID-19 pandemic brought by the severe acute respiratory syndrome coronavirus 2 (SARS-sensitive in observing newly infected individuals, due to numerous factors including, but not 77 limited to, the size of the contributing population, dilution of signal, and travel time (and associated 78 viral degradation) of sewage from toilets to sample collection points. The concept of NST has been 79 applied to school and university campuses, including the isolation of college dorms by collecting 80 samples from sewer lines exiting specific buildings prior to their mixing with other sewage 81 networks.

Following decisions to re-open campuses to in-person education for the 2020-2021 academic year, 83 many researchers began monitoring sewage for the presence of SARS-CoV-2 to inform decision-84 making by health officials and campus administrators [22] . We describe studies in the scientific 85 literature published in 2020-21 that document the use of WWS within school campuses, including 86 primary, secondary, and institutions of higher education. 87 Recently published research on the implementation of COVID-19 wastewater monitoring in school 88 and college campuses is summarized in Table 1 . Two recent studies [23, 24] describe WWS as a 89 tool that can support mitigation of SARS-CoV-2 transmission for primary and secondary schools.

Four additional preprints and published studies describe implementation of WWS on institutions 91 of higher education such as college campuses [11, 20, 25, 26] and temperature of wastewater, and water usage bills. Lastly, coordination with school facilities 123 departments helps to provide field human resources for routine collection of wastewater samples. It is recommended that samples be processed within 24-48 hours after sampling for a timely 146 turnaround of results. Various virus concentration methods, including ultracentrifugation, poly-147 ethylene glycol (PEG) precipitation, electronegative membrane filtration, adsorption-extraction, 148 and ultrafiltration have been used to concentrate SARS-CoV-2 in wastewater [32] [33] [34] . Methods 149 based on electronegative membrane filtration and PEG precipitation have been widely adopted in 150 school campus settings [11, 20, 22, 23, 25] . These methods do not depend on the availability of 151 expensive equipment such as ultracentrifuges and can be easily performed in a BSL-2 laboratory 152 with standard membrane filtration apparatus and tabletop centrifuge. RNA can be directly 153 extracted from the filters and/or pellets using commercially available RNA extraction kits. Overall, 154 it is important to maintain a consistent workflow in order to compare results across samples. 156 Most WWS programs used commercial kits for the extraction of RNA that combine physical (e.g., 157 bead-beating) with chemical (e.g., detergent) cell disruption methodologies. The most commonly 158 employed molecular assay to measure SARS-CoV-2 RNA is reverse transcriptasequantitative 159 polymerase chain reaction (RT-qPCR) using the CDC recommended N1 and N2 primer/probe sets 160 [35] . There are different platforms and reagents that may be used for RT-qPCR assays (Table 1) .

Wastewater contains a diverse range of PCR inhibitors including fats, proteins and humic/fulvic 162 acids, which can cause problems later during downstream processing during PCR [36, 37] . This Some of the biggest advantages of using wastewater surveillance for any pathogen or metabolite 225 are that WWS does not rely on health-seeking behavior, is not limited by health care access issues, 226 and in, the case of pathogens, might be useful in the pre-symptomatic and early symptomatic stages 227 if shedding is occurring. Because of this, wastewater surveillance can provide data for public health 228 decision making that is more robust and potentially timelier than current public health data streams 229 ( Figure 2 ).

Incorporating the wastewater surveillance data stream into public health decision making can be 231 done several ways, depending on the use case. In the case of COVID-19, the data generated from 232 wastewater surveillance can be used in at least three important ways, as follows: (1) in a 233 community, to monitor trends in SARS-CoV-2 infections and make public health decisions about 234 the need for changes in mitigation measures; (2) in a closed population, to look for any detection detection of SARS-CoV-2 in wastewater might be used to trigger the deployment of clinical 247 diagnostic testing within the school population. Given that others external to the school population 248 (e.g., an infected parent) might use the school restroom, it is possible that the clinical testing might 249 not result in the detection of any COVID-19 cases. Regardless of whether school-wide diagnostic 250 testing is done, the SARS-CoV-2 detection could also be used to trigger an increase in mitigation 251 measures such as increasing: masking, outdoor time, ventilation of indoor spaces, filtration of 252 indoor air, physical spacing, school-based vaccine clinics, and school communications campaigns.

Next, if the school has SARS-CoV-2 circulating at baseline, with or without a school-wide 254 diagnostic testing program, the above-mentioned mitigation measures could still be deployed. 

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