More than a year after the Centers for Disease Control and Prevention established its National Wastewater Surveillance System, the agency added wastewater data to its Covid-19 data tracker on Friday, providing a quick glimpse of whether the levels of coronavirus are rising or falling in hundreds of communities across the country.
People who are infected with the coronavirus shed the virus in their feces, and analyzing wastewater can help officials estimate how prevalent the virus is in a particular community and which variants are circulating.
And because people with the virus often begin shedding it before they seek care or testing — if they ever do — it can also provide an early warning system of coming surges or the circulation of new variants. Several communities detected Omicron in wastewater before any test samples from infected residents showed they had the variant.
“These data are uniquely powerful because they capture the presence of infections from people with and without symptoms, and they’re not affected by access to health care or availability of clinical testing,” Amy Kirby, the program lead for the National Wastewater Surveillance System, said at a news briefing on Friday.
The C.D.C., which established the system in September 2020, is now funding wastewater surveillance in 37 states, four cities and two territories, Dr. Kirby said. Not all of those jurisdictions have begun reporting data.
The new dashboard, which will be updated daily, provides a color-coded view of how the levels of virus in the wastewater have changed in participating communities over the previous 15 days.
But its coverage is limited, and provides an uneven view of the nation’s wastewater monitoring efforts. Of the 255 sites currently reporting data, many are concentrated in Wisconsin, Missouri and Ohio. More than a dozen states — including Idaho, Louisiana, Mississippi and Montana — are reporting no data at all.
Another 250 sites will be added to the dashboard in the next few weeks, Dr. Kirby said, though even then not all states will be covered.
“The real power of this program will be more evident in the coming weeks when hundreds more testing sites will begin submitting data,” she said.