Is Coronavirus Sewage Testing the Key to Slowing the Spread of COVID-19? Here's What Experts Say

Could one key to slowing the spread of COVID-19 be in our poop? Potentially, yes. Scientists across the US are currently conducting coronavirus sewage testing: they're taking samples of human waste from sewage plants and analyzing them to detect viral particles. If a high number of fecal samples test positive for the virus in a specific community, health officials could then take action locally to help prevent an outbreak.

Boston-based company Biobot, which describes itself as “the first company in the world to commercialize data from sewage,” has joined forces with researchers at MIT, Harvard, and Brigham and Women's Hospital to launch a pro bono program that maps COVID-19 across the country. To date, Biobot is working with about 330 facilities in 40 states, which represents approximately 10% of the US population.

The company launched its program after studies showed that SARS-CoV-2, the virus that causes COVID-19, is present in fecal matter (the Centers for Disease Control and Prevention confirms that the virus has been found in the feces of some patients diagnosed with COVID-19), and is thus gathering in city sewers.

While researchers have known since the early stages of the new coronavirus pandemic that the pathogen is present in fecal matter, the goal now is to determine exactly how much of it exists, to give a clearer picture of infection levels in the general population.

According to Biobot, the number of people infected with COVID-19 may be much higher than official figures suggest. Preliminary data, published on the preprint repository medRxiv on April 7, revealed that in a large metropolitan area in Massachusetts with 446 reported cases, their sewage-based method identified up to 115,000 unreported cases not known to health officials.

“We start the process by sending sampling kits to participating facilities across the US. These treatment plants are instructed to collect 24-hour composite samples and ship them back to Biobot for analysis,” Mariana Matus, PhD, CEO, and co-founder of Biobot, tells Health. At the lab, the Biobot team processes the sewage samples, then uses a technique called an RT-PCR protocol to detect the SARS-CoV-2 virus. The test results are given to participating communities via a weekly report.

“Where the virus is detected, we will provide an estimate of the prevalence of infection in the catchment tested,” says Dr. Matus. “The turnaround on the data is usually five days. It’s very important for our team to get the analyzed data back in the same week that the sample was collected, as the scope of the data shifts so quickly.”

Meanwhile, researchers in other countries have published promising findings from similar tests. A team in Paris sampled sewage for more than one month, observing a rise and fall in SARS-CoV-2 that tallied with the shape of the COVID-19 outbreak in the region (which remains under lockdown). The researchers said their study, published on medRxiv on April 17, was the first to show that the test can pick up a sharp rise in viral concentrations in sewage before cases erupt in health care facilities.

“The sewer gives epidemic outbreaks in real time,” public health expert Carol A. Winner, MPH, who has directed several federally funded community health-based initiatives and founded the Give Space movement in 2017, tells Health. “Feces and urine are constantly collected for study and although the coronavirus dissipates quickly, scientists are able to find microscopic particles of RNA from the virus. This allows environmental specialists to begin to link the outbreak levels to the levels sampled in the wastewater.”

As a relatively cheap, noninvasive way to identify and warn against future outbreaks, wastewater testing could provide enough information to guide decisions on protective and preventive strategies, such as social distancing.

“The data we find allows local communities and governments to measure the scope of the outbreak and take action,” says Dr. Matus. “As we are consistently finding results that are orders of magnitude greater than what has been clinically tested, even in our most conservative estimates, we are learning there is a large asymptomatic or low-symptomatic population.”

Dr. Matus believes that wastewater testing should be used alongside other testing methods to help track the effectiveness of interventions taken, and provide early warnings for reemergence of the coronavirus, if it does indeed have a seasonal cycle.

“Health specialists can use this type of information as another piece of the puzzle in making decisions about prevention and preparedness,” says Winner. “If environmentalists detect a spike in concentrations of the coronavirus in the sewage system, this signals the need for continued social distancing and possible quarantine and alerts them to ramp up medical preparedness. If they see a decline in concentrations, it could positively influence the mapping of the easing of restrictions.”

Until data from the sewage testing is peer-reviewed, however, it's unclear how valid the information is. Winner also points out that there's still a lot to be learned about the new coronavirus. “However, environmental surveillance of sewage systems is in place and is constant, so the technical practice itself offers a level of reliability,” she says.

Dr. Matus believes that the potential for data collection from sewage is huge. Biobot has developed hardware kits that can collect samples directly from sewer lines. “We’re working on scaling the technology to make it more widely available,” she says. “Eventually, the ability to test specific lines or at specific points in the sewer will help us pinpoint specific populations within a larger community.”

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.