Substantial fall for corona in wastewater
The concentration of coronavirus in Gothenburg wastewater has decreased significantly in one week. However, the level remains high, as the latest measurements and analyses from the University of Gothenburg show.
Two weeks ago, a turning point was noted. In the Gothenburg area, a massive, month-long rise in wastewater levels of SARS-CoV-2 had ended and was reversed.
Since then, the decline has continued. The current results are based on samples taken in the week from January 31 to February 6.
Still a high level
“We can now see an ongoing decrease, although the figure is still more than twice as high as any previous peak,” says Heléne Norder, adjunct professor at Sahlgrenska Academy, University of Gothenburg, and microbiologist at Sahlgrenska University Hospital.
The scientists have been investigating SARS-CoV-2 in the local wastewater since early February 2020: nearly two years. They collaborate with municipally owned Gryaab, which treats wastewater in Gothenburg and surrounding municipalities. The company sends the researchers weekly samples containing samples collected daily.
On an ongoing basis, the research group reports its results to care providers and the Infection Control Unit in Region Västra Götaland. To a varying degree, the raised concentrations of coronavirus in the wastewater, reflecting increased prevalence of COVID-19 in the community, have enabled prediction of health care services’ peak loads during the pandemic.
Important measurement
The measurements and analyses have become even more important as the overall change in public testing for COVID-19. With fewer getting tested, the number of confirmed cases tells us ever less about the actual spread of infection in society.
“Maybe what we’re now seeing is a decline due to so many people having been infected already. It’s not that our behaviors have simply changed in the sense of our becoming more cautious — rather the opposite,” Norder states.
Omicron continues to be the dominant coronavirus variant. Besides SARS-CoV-2, levels of three other viruses — influenza, respiratory syncytial virus (RSV), and norovirus (the “winter vomiting bug”) — are investigated. Neither influenza (A and B) nor the RS virus is currently present in the Gothenburg wastewater, while the norovirus level is relatively high.