August 20, 2020 -- The CDC and other federal government agencies are starting the National Wastewater Surveillance System to monitor how the coronavirus is spreading in communities.
State, local, tribal and territorial health departments will submit wastewater test data to a national database so public health officials can study trends, according to CDC guidance updated on Monday. The CDC is now developing that portal.
“SARS-CoV-2 can be shed in the feces of individuals with symptomatic or asymptomatic infection,” the CDC wrote. “Therefore, wastewater surveillance can capture data on both types of infection.”
The coronavirus doesn’t show up in treated water, such as pools and hot tubs, but it has been detected in untreated wastewater in several countries. So far, the CDC hasn’t found any cases where someone has contracted COVID-19 because of wastewater, according to the statement.
Monitoring wastewater will allow officials to see how COVID-19 is spreading in communities as a whole — and allow them to understand data in places where coronavirus testing is limited or not used enough. The CDC has tested sewage in the past to detect other diseases such as polio.
Sewage surveillance could also be a “leading indicator” of changes in COVID-19 spread in a community, according to the statement. However, sewage testing can’t be used to reliably or accurately predict the number of people in an area who may be infected.
About 80% of U.S. households are served by community-level sewage collection systems. The surveillance program won’t include homes that use septic tanks or separate systems that treat their own waste, such as some prisons, hospitals and universities.
In addition, the monitoring system may not detect low levels of infection in a community. Public health officials are still learning the “lower limits of detection,” or the lowest number of infected individuals required to detect the virus in sewage. The new surveillance system may help the CDC to better understand that.
“More data on fecal shedding by infected individuals over the course of disease are needed to better understand the limits,” the CDC wrote.