As the United States enters year three of the coronavirus pandemic, disease trackers are trying to stay one step ahead of the constantly evolving virus — by hunting for it in feces.
In Maine, hospitals are on alert for a potential surge of patients, tipped off by consistently rising levels of the coronavirus in wastewater. In Ohio, which has used sewage surveillance to identify new variants, authorities are tracking substantial increases at a dozen of the state’s 71 monitoring sites, including south of Columbus. In Houston, steady increases have not been accompanied by a rise in hospitalizations, the first time in almost two years, suggesting that vaccinations and previous infection may be keeping people out of hospitals.
The secrets of the virus can be found in wastewater because most infected people shed tiny pieces of virus when they use the toilet. So regularly analyzing wastewater from sewage treatment plants allows scientists to measure when those levels are rising or falling — and what variants are present — about four to six days before people start testing positive.
Wastewater surveillance has long been used to contain polio outbreaks, and its potential for helping stanch the coronavirus was recognized at the start of the pandemic. Now, sewage monitoring has gained increasing importance as prevention measures — mask mandates and social distancing, for instance — vanish in much of the country at the same time that the highly transmissible omicron subvariant known as BA.2 fuels a rise in coronavirus cases in some regions, including the Northeast.
With official reporting of cases and testing data becoming less frequent and less reliable, especially as people test at home, officials need other ways to track the virus.