When you think of tracking the prevalence and spread of the novel coronavirus disease, COVID-19, you imagine labs testing individual nasal swabs, but an unlikely star is emerging as a powerful tool to track the spread of this new disease: wastewater. Researchers can analyze a community’s wastewater to detect viral particles excreted by individuals infected with COVID-19. Data suggests that an infected person will excrete into wastewater millions, if not billions of viral genomes each day. These viral particles can then survive two to four days as they travel through the wastewater system. 

Detecting the novel coronavirus in wastewater can be one of the earliest indications of the virus’s spread in a community. The virus can start being released as early as the third day of infection, even before any symptoms develop. Analyzing the virus in wastewater also provides a way to detect infections in those who are asymptomatic or only experience mild symptoms and would not otherwise seek testing. As revolutionary as this technique may seem, using wastewater to detect viruses at a community level has been used for over three decades, first to track polio incidence and since then for norovirus. 

In a recent episode of The Outfall podcast, we talked to two pioneering researchers about the unique advantages of using wastewater as an epidemiological tool and how South Carolina is taking a leading role. Dr. Sean Norman, an associate professor in the Department of Environmental Health Sciences at the University of South Carolina has spent the last 10 years tracking antibiotic resistant bacteria through wastewater treatment plants. However, Dr. Norman received a call from the Centers for Disease Control and Prevention earlier this year that caused him to shift his lab focus to the novel coronavirus and its presence in wastewater.

“If you can’t go in and individually test an entire population of people, there’s really not necessarily a better way than using sewage because a sewer shed is collecting the information from a population of people throughout a community,” explained Dr. Norman. By collecting this viral information, researchers
can develop predictive models and alert health officials to new outbreaks, often even before individuals would know that they were infected.
This means policymakers, public health officials, and healthcare workers could have an early warning system and be prepared for a new disease surge. 

Over 2,000 miles away from Dr. Norman’s lab, Dr. Ian Pepper, an environmental microbiologist at the University of Arizona, has been analyzing samples from 15 different wastewater treatment plants from across the country. He has been collecting two samples a week from a wastewater treatment plant in Tucson. Over this time, Dr. Pepper has been able to track changes in the concentration of the virus and sees immense public health potential from this wastewater tool. Dr. Pepper explains that the presence of coronavirus in sewage is a leading indicator of pandemics as opposed to death, which is the lagging indicator. The intelligence that wastewater can provide gives health officials invaluable time to prepare a response and potentially save lives. 

Closer to home, Dr. Norman is also analyzing a number of wastewater treatment plants. He is sampling approximately eight plants in South Carolina, two in Texas, and one in California. In less than 24 hours, Dr. Norman can detect the amount of the novel coronavirus in an entire community’s wastewater. Dr. Norman explains that a sample of wastewater gives a unique snapshot of that community. Understanding the variables that affect that snapshot are important, such as total suspended solids and the percentage of residential versus industrial influence. Once these variables are accounted for, models can be developed to understand the percentage of the population infected
by the virus.

“I’m most curious about seeing if we can adapt this into a model to be able to assess the true percentage of the population that’s infected by the virus. That to me is the golden ticket for the work that we’re doing. If we can do that, then we can make it a predictive model; then it becomes an applied public health tool that might be able to be adopted by policymakers.”

– Dr. Sean Norman

Since this episode was produced, many more utilities, cities, and even universities across the state have begun monitoring their wastewater for the novel coronavirus. Researchers are sampling, analyzing,
and dialing in on the right information to turn this data into models that can become a frontline public health tool.
We are following this research closely and are excited to produce more episodes to follow up on how this viral epidemiology
is aiding the COVID-19 response.

The Outfall is a water podcast for everyone curious about water, wastewater, and infrastructure. Our water world is diverse and so is our audience and topics. Our goal is to be more fun than serious, more short than long, and hopefully more lively than dull. It’s easy to find us: https://theoutfall.com. You can listen from whatever platform or program you use like Apple Podcasts or Spotify. Make sure to click “Subscribe” to get notified when new episodes come out and have them automatically added to your listening stream.