UM, Stanford study early warning system for coronavirus through sewage

As the world works to stem the tide of the coronavirus, researchers are racing to better understand the virus, its transmission, and how to stop it.

One potential answer could be in the water — wastewater, to be precise.

Though the COVID-19 is a respiratory disease, researchers at the University of Michigan and Stanford University say that people who have contracted COVID-19 shed the genetic material of the virus through their waste and into a community's sewage system. 

That's why they are looking for early signs of the novel coronavirus in the wastewater of some California and Midwest communities to develop a tool that might inform a community of the virus' presence before a widespread outbreak.

If successful, it would be an early-warning system that detects when a virus is circulating before sick people appear in hospitals. That could prompt quicker and shorter calls for social isolation without crippling the economy.

"It would be like a real-time assessment of what is happening in the community," said Krista Wigginton,  a UM civil and environmental engineering associate professor who is currently a visiting professor at Stanford.

More than a third of U.S. counties don't have a single reported case of the COVID-19, the disease caused by the virus, according to a surveillance system set up by Johns Hopkins University. But because symptoms can take 2-14 days to present, an absence of positive tests does not mean the virus isn't already circulating.

Wigginton, along with her Stanford colleagues, landed a $200,000 Rapid Response Grant from the National Science Foundation and hope to develop a way of detecting the virus in the environment within a month. How soon the surveillance system might be available isn't yet clear.

One of the lead researchers, Wigginton has studied coronaviruses for the last several years in the family of SARS, MERS and strains of the common cold. She said not a lot is known about their presence, persistence and transfer in the environment— either indoors or outdoors.

Right now, the data currently reflecting the spread of COVID-19 infections is based entirely on tests and hospitalizations, meaning it is dependent on sick people and the prevalence of testing.

"That is probably delayed on when people are actually getting the illness," said Wigginton. "That's often one or two weeks after they have been infected with the virus, maybe longer."

If wastewater surveillance can detect the prevalence of the virus, a community can make informed decisions, especially if the pandemic comes in waves. Early detection could inform—before ICU admissions spike—when citizens need another period of social distancing, said Alexandria Boehm, a Stanford professor of environmental engineering and another lead investigator. 

"Having a better way to know when social distancing is required would be helpful," said Boehm. "Our hope is that we can detect an uptick in cases with this tool faster than we can through clinical testing. We don't know that for sure, but that's the hypothesis. 

Boehm added that the earlier virus transmission is stopped, "the shorter periods of time you'll need strict social distancing measures and the less inconvenient it will be for a community." 

The research comes as COVID-19 has caused a worldwide pandemic that has infected more than 700,000 people around the globe and claimed the lives of nearly 34,000 people, according to the Johns Hopkins Coronavirus Resource Center. In Michigan, the virus has infected 5,500 people and killed 132. 

The virus, for which no vaccine has been approved, is so highly contagious that it has shut down much of public life. On Sunday, President Donald Trump extended the voluntary national shutdown for a month. 

Researchers have studied pathogens in sewage for decades but only recently started using it to inform and protect public health, said Joseph Eisenberg, chair and professor of epidemiology in UM's school of public health. He pointed to sewage surveillance used in Israel to monitor poliovirus circulation.

"It is a very sensitive way to monitor the transmission of pathogens," said Eisenberg.

It’s not completely recognized that environmental surveillance could be a public health tool for some pathogens, Eisenberg added

"It has a lot of promise," he said.

Dr. Mona Hanna-Attisha, whose research helped expose the Flint water crisis, said the research underway to detect COVID-19 in wastewater has potential. She emphasized that wastewater is headed for cleansing at wastewater treatment plants and is not the same as drinking water.

“The armory of public health has been disseminated for decades," Hanna-Attisha said. "Too often we slowly react to a public health crisis, rather than invest in the innovation, science and technology to better proactively prevent such disasters. A project like this has the potential to creatively bolster our public health surveillance systems to more timely identify and respond to emerging threats.” 

Nasa Sinnott-Armstrong, a Stanford doctoral working on the project, said their work could offer a clearer picture of how the disease is spreading because it could pick up evidence of the virus even when there are more mild cases of disease, or even those that bring no symptoms at all. 

"For epidemiologists interested in the prevalence and incidence of COVID-19, our methodology offers an estimate that does not rely on testing every individual, nor is it as prone to measurement bias," said Sinnott-Armstrong. "We could identify areas with rapidly increasing cases as a warning system to the health care system. Finally, these numbers can help epidemiologists model the trajectory of the pandemic with far less testing burden on our health care system."