Coronavirus level in wastewater remains high but shows signs of decline

This week’s results of the wastewater analysis led by the University of Tartu reveal that the concentration of coronavirus in samples taken from larger cities of Estonia has started to decline. However, the virus is widely spread all over Estonia and still abundant in the wastewater, so the situation does not seem to be easing just yet.

According to the principal investigator, Professor of Technology of Antimicrobial Compounds of the University of Tartu Tanel Tenson, virus concentration in wastewater has risen to such a high level that the readings will probably remain high for some time even if the currently noticeable slight decline continues. “The concentration of coronavirus started to grow rapidly in mid-November last year. This was followed by a surge in the number of infections. If we compare the current infection figures and wastewater analysis results with those of November, we still have a long way to go to get back to the same level. The number of the infected continues to be high throughout Estonia and it is therefore necessary to be careful everywhere to avoid infection,” Tenson explained.

Wastewater samples are collected at the beginning of every week in all county centres, cities with more than 10,000 inhabitants and, if necessary, in smaller settlements. Samples taken from larger cities reflect the situation of wastewater passing through the treatment plant over 24 hours, giving a reliable overview of the infection level in the city. In smaller places, spot samples are taken, showing the virus level in wastewater at the moment of sampling. Spot samples are more easily affected by various factors and should therefore be used over several weeks to estimate the trend, rather than get a definitive picture of the current situation.

The study is a tool helping the Health Board monitor changes in the outbreak dynamics and discover hidden outbreaks. It gives early information for estimating the spread of the virus before clinical cases are detected. The Health Board is regularly informed of the results.

In collecting the samples, the University of Tartu cooperates with the Estonian Environmental Research Centre and water companies operating the waste water treatment plants of Estonian cities. The samples are analysed at the laboratories of the University of Tartu Institute of Technology.

For more information and the interactive map with the previous results of the study, see the home page of the study “Detecting coronavirus in waste water”.

Further information: Tanel Tenson, Professor of Technology of Antimicrobial Compounds, University of Tartu, 5344 5202,