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New decrease in coronavirus levels in wastewater


In the Gothenburg area, the coronavirus concentration in the wastewater has fallen sharply. This is revealed by the latest results and analyses from the University of Gothenburg.

Since mid-May, the relative level of SARS-CoV-2 in the Gothenburg wastewater increased every week. The peak recorded at the end of June was still far below the extreme record high of the fourth pandemic wave. Nonetheless, it exceeded the top readings of the previous pandemic waves.

The latest measurement shows a relatively marked decline in the wastewater concentration of coronavirus. If the previous pattern persists, the increasing number of COVID-19 cases reported in the past few weeks may be expected to decrease in a week or two.

Heléne Norder, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg.
Photo: Elin Lindström

Fewer cases of illness soon

“Well, that’s the hope now that the levels are falling again; and we can only hope they will stay low,” comments Heléne Norder, research leader and microbiologist, on the latest weekly results, based on samples taken in the week of June 27 to July 3.

The wastewater SARS-CoV-2 investigations in Gothenburg have been performed since February 2020. They are carried out by a research group at the University of Gothenburg’s Sahlgrenska Academy in collaboration with Gryaab, the municipally owned company in charge of treating wastewater in Gothenburg and its surrounding municipalities.

Every week, Gryaab provides the researchers with a composite sample made up of wastewater samples collected daily. The group, which then measures and analyzes the sample, reports directly to Infection Control and care providers in Västra Götaland.

Enterovirus remains high

Coronavirus in the wastewater is an indicator of how much virus and sickness is present in the community. However, the association between virus in the wastewater and the proportion of people who are severely ill has successively decreased with the growing strength of vaccination protection.

In addition to SARS-CoV-2, the level of enterovirus — now relatively high for the season — is investigated. Enterovirus can cause a wide range of symptoms, from the common cold to inflammation of the pericardium, meningitis, and paralysis. However, the majority get only mild symptoms.

In contrast, the measurements taken in the Gothenburg wastewater show a low level of adenovirus, which causes respiratory infections and is suspected of also causing hepatitis in children.