Early warning of a COVID-19 surge on a university campus based on wastewater surveillance for SARS-CoV-2 at residence halls

Abstract

As COVID-19 continues to spread globally, monitoring the disease at different scales is critical to support public health decision making. Surveillance for SARS-CoV-2 RNA in wastewater can supplement surveillance based on diagnostic testing. In this paper, we report the results of wastewater-based COVID-19 surveillance on Emory University campus that included routine sampling of sewage from a hospital building, an isolation/quarantine building, and 21 student residence halls between July 13th, 2020 and March 14th, 2021. We examined the sensitivity of wastewater surveillance for detecting COVID-19 cases at building level and the relation between Ct values from RT-qPCR results of wastewater samples and the number of COVID-19 patients residing in the building. Our results show that weekly wastewater surveillance using Moore swab samples was not sensitive enough (6 of 63 times) to reliably detect one or two sporadic cases in a residence building. The Ct values of the wastewater samples over time from the same sampling location reflected the temporal trend in the number of COVID-19 patients in the isolation/quarantine building and hospital (Pearson's r < -0.8), but there is too much uncertainty to directly estimate the number of COVID-19 cases using Ct values. After students returned for the spring 2021 semester, SARS-CoV-2 RNA was detected in the wastewater samples from most of the student residence hall monitoring sites one to two weeks before COVID-19 cases surged on campus. This finding suggests that wastewater-based surveillance can be used to provide early warning of COVID-19 outbreaks at institutions.

Keywords: COVID-19; Campus; Residence hall; SARS-CoV-2; Wastewater surveillance.

Graphical abstract

Fig. 1

Sampling sites distribution on Emory Campuses. a. Atlanta Campus, including the Emory University Hospital building sampling site and isolation/quarantine building sampling site. b. Clairmont Campus. c. Oxford Campus.

Fig. 2

Wastewater surveillance results for grab samples and Moore swab samples compared to the number of COVID-19 patients in the hospital building between July 13th, 2020 to March 14th, 2021.

Fig. 3

Wastewater surveillance Ct value results for grab samples and Moore swab samples compared to the number of COVID-19 patients in the hospital building.

Fig. 4

Wastewater surveillance results from Moore swabs placed near the isolation/quarantine building and the number of students isolated/quarantined. The number of students in the isolation/quarantine building included those who tested positive for COVID-19 and close contacts who tested negative.

Fig. 5

Wastewater surveillance Ct value results for Moore swab samples with the number of students in the isolation/quarantine building.

Fig. 6

Wastewater surveillance results of residence hall and case data at Emory University Campus. Wastewater surveillance results are displayed with blue (negative) and red (positive) tiles by sampling site. Data were aggregated weekly. Numbers of confirmed cases are marked in the tiles corresponding to their residence halls. Some residence halls shared data of confirmed cases and have the same manhole index number following the residence hall name. Weeks without wastewater surveillance results are left blank.