Averting an Outbreak of SARS-CoV-2 in a University Residence Hall through Wastewater Surveillance

Abstract

A wastewater surveillance program targeting a university residence hall was implemented during the spring semester 2021 as a proactive measure to avoid an outbreak of COVID-19 on campus. Over a period of 7 weeks from early February through late March 2021, wastewater originating from the residence hall was collected as grab samples 3 times per week. During this time, there was no detection of SARS-CoV-2 by reverse transcriptase quantitative PCR (RT-qPCR) in the residence hall wastewater stream. Aiming to obtain a sample more representative of the residence hall community, a decision was made to use passive samplers beginning in late March onwards. Adopting a Moore swab approach, SARS-CoV-2 was detected in wastewater samples just 2 days after passive samplers were deployed. These samples also tested positive for the B.1.1.7 (Alpha) variant of concern (VOC) using RT-qPCR. The positive result triggered a public health case-finding response, including a mobile testing unit deployed to the residence hall the following day, with testing of nearly 200 students and staff, which identified two laboratory-confirmed cases of Alpha variant COVID-19. These individuals were relocated to a separate quarantine facility, averting an outbreak on campus. Aggregating wastewater and clinical data, the campus wastewater surveillance program has yielded the first estimates of fecal shedding rates of the Alpha VOC of SARS-CoV-2 in individuals from a nonclinical setting. IMPORTANCE Among early adopters of wastewater monitoring for SARS-CoV-2 have been colleges and universities throughout North America, many of whom are using this approach to monitor congregate living facilities for early evidence of COVID-19 infection as an integral component of campus screening programs. Yet, while there have been numerous examples where wastewater monitoring on a university campus has detected evidence for infection among community members, there are few examples where this monitoring triggered a public health response that may have averted an actual outbreak. This report details a wastewater-testing program targeting a residence hall on a university campus during spring 2021, when there was mounting concern globally over the emergence of SARS-CoV-2 variants of concern, reported to be more transmissible than the wild-type Wuhan strain. In this communication, we present a clear example of how wastewater monitoring resulted in actionable responses by university administration and public health, which averted an outbreak of COVID-19 on a university campus.

Keywords: COVID-19; RT-qPCR; SARS-CoV-2; wastewater.

FIG 1

Concentration of the SARS-CoV-2 N1 gene target in wastewater superimposed onto COVID-19 cases in the Windsor-Essex region, plotted as a histogram. The N1 gene concentration is a 7-day running average of aggregate data from five WWTPs in Windsor-Essex, with the data weighted by population served (red line). These data are publicly available on a dashboard updated weekly (44). Sampling of residence hall wastewater by grab samples over 7 weeks yielded no detections of SARS-CoV-2 (pink circles). Following deployment of passive samplers, SARS-CoV-2 was detected in the residence hall sewer, plotted as the ratio of gene copies (gc) of SARS-CoV-2:PMMoV (blue circles; ±standard error [SE] where replicate samples were analyzed).

FIG 2

Concentration of PMMoV in wastewater from a university residence hall and as aggregate data across five WWTPs in the Windsor-Essex region. The data are presented as box and whisker plots showing the median gene concentrations. Vertical boxes around each median show the upper and lower quartiles, whereas whiskers extend from the 10th to 90th percentile. Potential outliers are shown as discrete points.