Significant increase of detected COVID-19 in Stockholm wastewater

The concentration of coronavirus found in municipal wastewater has doubled during the recent weeks and has now reached similar levels as in May 2020. New research confirms that wastewater analyzes can warn of future virus outbreaks in society.

In a collaboration between SciLifeLab, Royal Institute of Technology (KTH), and Stockholm Vatten och Avfall, scientists have followed the development of COVID-19 in Stockholm since April, by periodically collecting wastewater samples from treatment plants in Henriksdal and Bromma. The content has then been analyzed through genetic analysis. 

“We see similar, distinct increases in the data during week 39, at the end of September. Then the virus concentration started to approach the levels we saw in May”, says Cecilia Williams (SciLifeLab/KTH).

As the number of people tested for the virus was ramped up greatly during August and September, the high number of identified infected individuals in the community could be a direct result of increased testing.

Now however, the researchers can confirm that the recent observed increase in COVID-19 cases is reflected in the wastewater samples, and not due to the increased testing.

“My interpretation is that this latest increase definitely reflects an increased number of infected individuals in society. It will be interesting to see the results next week, if the trend continues and the number of COVID-19 cases continues to increase, says Cecilia Williams.

The water analysis results also strengthen the Public Health Agency’s conclusions earlier this year, regarding the connection between the number of tests and those found infected.

“We see in the graph that a large peak of confirmed cases of COVID-19 in Stockholm took place during the same period as testing in society increased in June. This was while the amount of virus particles in the water during the same time period clearly decreased. That result supports the Swedish Public Health Agency’s conclusion”, says Cecilia Williams.

Read the full press release from KTH (in Swedish)

Photo: Stockholm vatten och avlopp


Last updated: 2020-10-08

Content Responsible: David Gotthold(