Making waves: Wastewater surveillance of SARS-CoV-2 for population-based health management

Abstract

Worldwide, clinical data remain the gold standard for disease surveillance and tracking. However, such data are limited due to factors such as reporting bias and inability to track asymptomatic disease carriers. Disease agents are excreted in the urine and feces of infected individuals regardless of disease symptom severity. Wastewater surveillance - that is, monitoring disease via human effluent - represents a valuable complement to clinical approaches. Because wastewater is relatively inexpensive and easy to collect and can be monitored at different levels of population aggregation as needed, wastewater surveillance can offer a real-time, cost-effective view of a community's health that is independent of biases associated with case-reporting. For SARS-CoV-2 and other disease-causing agents we envision an aggregate wastewater-monitoring system at the level of a wastewater treatment plant and exploratory or confirmatory monitoring of the sewerage system at the neighborhood scale to identify or confirm clusters of infection or assess impact of control measures where transmission has been established. Implementation will require constructing a framework with collaborating government agencies, public or private utilities, and civil society organizations for appropriate use of data collected from wastewater, identification of an appropriate scale of sample collection and aggregation to balance privacy concerns and risk of stigmatization with public health preservation, and consideration of the social implications of wastewater surveillance.

Keywords: Data privacy; Fecal-oral transmission; Health management; SARS-CoV-2; Wastewater surveillance.

Fig. 1

Wastewater-based surveillance for population-based health management. The SARS-CoV-2 virus enters the sewerage system through fecal shedding. Wastewater sampled at maintenance holes or the treatment plant represents an aggregate and average of shed viral titers at the level of the neighborhood, region or municipality. A composite sample collected over 24 h captures the daily flux from the population and is purified from a defined volume to recover the RNA associated with wastewater-borne viral particles. The viral genomes are measured in the purified RNA sample using a molecular assay such as quantitative PCR and used to determine the number of viruses in the defined volume of sampled wastewater. Wastewater viral levels are then combined with wastewater flow rates and estimates of excreted viral load per toilet flush to model infection prevalence in the sampled community. Importantly, this estimate of prevalence reflects the excreted viral load from both sick and asymptomatic individuals and complements essential individual testing. As ongoing research refines these modeling approaches, it may become possible to gain actionable insights from viral levels in wastewater for implementing health-protective measures at the neighborhood or regional level. Concurrently, issues of privacy must be considered to ensure appropriate use of wastewater-based surveillance data, which holds the potential to become a new source of “big data” in our increasingly connected world.