Coronavirus amount in waste water varies considerably between regions

This week’s results of the waste water monitoring study led by the University of Tartu show that while the overall virus situation remains fairly stable, regional variations can be observed. South Estonia continues to stand out with higher virus amounts, but no virus was found this time in samples from the islands of Hiiumaa and Saaremaa.

According to the lead researcher of the study, Professor of Technology of Antimicrobial Compounds of the University of Tartu Tanel Tenson, the index describing the average situation in Estonia remains more or less at the same level compared to the previous few weeks. Although fewer samples with very high and moderate virus levels were detected, the number of samples with high virus content has slightly increased within a week. Regional differences are noticeable between western and southern Estonia. While the virus amounts in the western counties have decreased, South Estonia continues to show higher levels than the Estonian average. “It’s good news that the virus amount has slightly decreased in almost all larger settlements. However, the towns of Põlva and Tõrva stand out for their very high virus levels compared to other places,” said Tenson.

How and where are the samples collected?

Waste water samples are collected at the beginning of every week in all Estonian county centres, cities with more than 10,000 inhabitants and, if necessary, in smaller settlements. Samples taken from larger cities reflect the situation of waste water 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 waste water 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 to estimate 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 about the previous results of the study, see the home page of the study “Detecting coronavirus in waste water”.

The waste water study is funded by the European Regional Development Fund from the EU measure to respond to the Covid-19 pandemic.

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