When Case Reporting Becomes Untenable: Can Sewer Networks Tell Us Where COVID-19 Transmission Occurs?

Monitoring SARS-CoV-2 in wastewater is a valuable approach to track COVID-19 transmission. Designing wastewater surveillance (WWS) with representative sampling sites and quantifiable results requires knowledge of the sewerage system and virus fate and transport. We developed a multi-level WWS system to track COVID-19 in Atlanta using an adaptive nested sampling strategy. From March 2021 to April 2022, 868 wastewater samples were collected from influent lines to wastewater treatment facilities and upstream community manholes. Variations in SARS-CoV-2 concentrations in influent line samples preceded similar variations in numbers of reported COVID-19 cases in the corresponding catchment areas. Community sites under nested sampling represented mutually-exclusive catchment areas. Community sites with high SARS-CoV-2 detection rates in wastewater covered high COVID-19 incidence areas, and adaptive sampling enabled identification and tracing of COVID-19 hotspots. This study demonstrates how a well-designed WWS provides actionable information including early warning of surges in cases and identification of disease hotspots.

A Novel COVID-19 Early Warning Tool: Moore Swab Method for Wastewater Surveillance at an Institutional Level

SARS-CoV-2 is a respiratory virus but it is also detected in a significant proportion of fecal samples of COVID-19 cases. Recent studies have shown that wastewater surveillance can be a low-cost tool for management of COVID-19 pandemic and tracking COVID-19 outbreaks in communities but most studies have been focusing on sampling from wastewater treatment plants. Institutional level of wastewater surveillance may serve well for early warning purposes since cases can be tracked and immediate action can be executed in the event of positive signal. In this study, a novel Moore swab method was developed and used for wastewater surveillance of COVID-19 at institutional level. Among the 219 swab samples tested, 28 (12.8%) swabs collected from the three campuses and two buildings were positive for SARS-CoV-2. Further individual clinical diagnosis validated the wastewater results and indicated that this method was sensitive enough to detect 1-2 cases in a building. In addition, comparison between grab and Moore swab methods from the hospital sewage line indicated that Moore swab method was more sensitive than the grab sampling method. These results suggest that the Moore swab is a sensitive, practical, and easy to use early warning tool for COVID-19 surveillance especially in low-resource settings and at an early stage of infection in communities.