As nations around the world develop strategies to combat the coronavirus, policymakers and scientists determine the scope of the problem as precisely as possible. All countries keep statistics about active and cured cases, but it’s generally acknowledged that the number of infected people, some of whom may be completely asymptomatic, is likely far greater. So the search for analytic tools goes on.
Enter wastewater. In the past, sewer water has been analyzed to determine the extent of drug use in New York or London, for instance. The corona virus, as a research team led by Dr. Christian Drosten of Charité hospital in Berlin has found out, can be detected in stool samples and later in wastewater. In this state, the material is then no longer infectious. Wastewater samples could therefore safely be used to detect the spread of the corona virus. Research to this end is currently going on in Britain, the Netherlands, Sweden and Switzerland as well as Germany. Among the German institutions involved are the Helmholtz Center for Environmental Research (UFZ), the German Association of Water Management, Sewage and Waste (DWA) and Technical University of Dresden.
The project is currently engaged in a test phase with some 20 wastewater treatment plants in places like Cologne, Leipzig, Dresden and the Eiffel-Rur region. The tests concern the entire analytic spectrum from collecting and preparing samples to polymerase chain reaction (PCR) analysis and model projections.
The UFZ says that by analyzing samples from around 900 wastewater treatment plants it could cover some 80 percent of sewage and a majority of the German populace. This, adds the institute, could function as a kind of early warning system.
The main challenges here are how to detect minute amounts of the corona virus and its RNA, how to best prepare samples and how to automatize procedures. The UFZ and the TU Dresden are working intensively on a wastewater-specific testing procedure and model systems for handling the expected flow of data.
“It will be decisive to achieve a detection sensitivity for Sars-CoV-2 that doesn’t only yield useful results when concentrations are high,” says UFZ virologist René Kallies. “Initial results have made us cautiously optimistic that we go below the state-set limit of 50 infected individuals per 100,000 residents of a given area.”
But Kallies cautioned that a fully operational wastewater detection was still a ways off despite researchers working as fast as they can.