Coronavirus levels are rising at 38 percent of wastewater sampling sites in the U.S. that submit data to the CDC.
Wastewater surveillance of SARS-CoV-2 RNA levels in the U.S. is still limited, with most of the 688 sampling sites concentrated in the Midwest and Northeast, the CDC's surveillance map shows.
For the 15-day period ending March 10, 38 percent of sampling sites saw an increase in virus levels. Sixty-two sites, representing 15 percent of the sampling sites that report to the CDC, saw virus levels increase by at least 1,000 percent during the 15-day period. Several of those sites were in Illinois and Ohio.
The levels in sampling sites in certain areas aren't uniform, however. There are counties, such as Cook County in Illinois, where some sampling sites show an increase, and others show a decrease.
Wastewater sampling measures how much of the virus is in sewer water and is used to gauge how prevalent the virus is in certain communities.Infected individuals shed the virus in their feces and may do so before they test positive.
With more than a third of U.S. sampling sites showing an increase in virus levels, Amy Kirby, PhD, the head of the CDC's wastewater surveillance program, told Bloomberg, "It's too early to know if this current trend will continue or whether we'll see a corresponding increase in reported cases across the country. … We encourage local health officials to monitor their numbers closely and use these data as an early warning sign if wastewater levels continue to increase."
COVID-19 cases, deaths and hospitalizations continue to decline in the U.S, though experts are concerned rising figures in Europe — driven at least in part by BA2, the omicron subvariant — may signal what could play out here in the coming weeks.
"Great to see U.S. COVID-19 hospitalizations down to 23,000 and approaching their pandemic low. But indicators from the new wave in Europe and U.S. wastewater surveillance suggest this may be short-lived," Eric Topol, MD, founder and director of the Scripps Research Translational Institute in San Diego, tweeted March 14.
Eric Feigl-Ding echoed Dr. Topol's concern in a series of March 14 tweets, noting the "sharp reversal" in wastewater levels in the U.S. He said the data suggests a parallel to the situation in Europe, and that a wave of BA2 infections will follow in the U.S. "How soon/big is the question," he tweeted. He is a senior fellow at the Federation of American Scientists in Washington, D.C., and former faculty member at Harvard Medical School in Boston.
The seven-day average for new cases was 33,852 as of March 14, levels not seen since July 2021, data from The New York Times shows.