"So far, we have analyzed samples from nine treatment plants in Sweden and discovered the virus in all places", says Annelie Hedström, Associate Professor in Urban Water Engineering at Luleå University of Technology.
Following preliminary studies that discovered the presence of the virus in feces from hospital patients, several research groups have reported the presence of viral genetic material (in non-infectious form) in wastewater.
"Particularly interesting are the studies that report the presence of viral material before cases of disease from the catchment area have been reported, which indicates that this method could support an early detection of corona outbreaks", says Annelie Hedström.
Whilst there are still many unknowns in this new area of research, recent studies in Spain and the Netherlands indicate a 5-10 day delay between detection of the virus in wastewater and clinical confirmation of cases in people. Regular collection and analysis of wastewater may therefore support routine clinical testing by rapidly identifying the occurrence of the virus at a local scale and inform public health activities to prevent a future outbreak of the disease.
"We took two repeated samples in early June and July. Since then, concentrations have fallen as the number of infected people has been low in the community during the summer. Therefore, we have not taken any more samples after that but may become relevant now when the number of infected people is increasing again. An interesting aspect of this is to try to link the concentrations to the proportion of those infected in society. This is something we are thinking about today", says Annelie Hedström.
It is within the European research framework Norman Score sewage surveillance initiative that Luleå University of Technology together with the Swedish University of Agricultural Sciences and Uppsala University investigated the presence of SARS-CoV-2, ie the virus that causes covid-19, in wastewater.