Tracking COVID-19 with Wastewater Surveillance

Understanding the full extent of community spread during the COVID-19 pandemic has remained an ongoing challenge for public health officials. Many municipalities were slow to begin testing and continue to lack adequate diagnosis. This is compounded by the fact that the novel coronavirus (SARS-CoV-2) has an incubation period of 2-14 days, which creates a lag in hospitalizations and puts tremendous strain on our healthcare system. 

Testing and hospitalizations aren’t enough to fully understand the extent of community spread because people with mild or asymptomatic disease are omitted. An estimated 20% of COVID-19 infections are asymptomatic but still contagious. To provide public health officials with more accurate information, many municipalities are implementing a rapidly developing science known as wastewater-based disease surveillance.

While wastewater testing has been used to detect diseases since the 1990s, particularly with the poliovirus, the rise of COVD-19 demands widespread advancement. Wastewater surveillance can be a strong indicator of the changes in a community’s COVID-19 burden — independent of clinical testing and healthcare visits.

National Wastewater Surveillance System

In response to the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) and the US Department of Health and Human Services (HHS) have created the National Wastewater Surveillance System (NWSS). The data generated by NWSS will complement existing data sources and help public health officials better understand community spread of COVID-19. 

How Can Wastewater Surveillance Help COVID-19?

Wastewater includes water from commercial and residential use (toilets, sinks, showers) as well as water from non-household sources (rainwater and industrial). Nearly 80% of the United States is served by municipal sewage collection systems. These facilities can test wastewater for RNA from SARS-CoV-2, the virus that causes COVID-19. 

If implemented properly, wastewater surveillance can provide public health officials with real-time information about the extent of COVID-19 in local populations.

Wastewater surveillance has many benefits. It is a cost-effective and efficient means of collecting an aggregate community sample, particularly in communities where clinical testing is underutilized or unavailable. It can also help to avoid the biases of certain epidemiological indicators. But perhaps the most meaningful benefit of wastewater surveillance is that it reveals the prevalence of COVID-19 in individuals with symptomatic or asymptomatic infection. This allows for more accurate insight about community spread.

Once COVID-19 vaccines become widely available, wastewater surveillance can be used to monitor fluctuations at the local level. Additionally, it can be used to prioritize the deployment of vaccines based on which communities need it the most. But even now, the data collected from wastewater surveillance can facilitate social distancing measures to mitigate exponential growth in transmissions until the world is well on the other side of the pandemic.

Learn More About Wastewater-Based Disease Surveillance

The successful implementation of a COVID-19 wastewater surveillance strategy should be driven at the local level. It requires cooperation between health officials and municipal wastewater treatment plants. 

Wastewater surveillance is meant to complement other surveillance activities and inform proactive public health actions. In other words, intervention should not be based on wastewater data alone, but should consider testing and other healthcare-seeking actions.

Visit the CDC website to learn more about wastewater-based disease surveillance and how municipal wastewater providers can use this rapidly advancing science to aid public health officials and the populations they serve.