Coronavirus concentration in wastewater has increased again

This week the results of the wastewater study led by the University of Tartu show again an increase in the spread of the coronavirus. The amounts of virus have increased most of all in samples collected from southern and western Estonia.

While last week’s analysis results gave some hope that the virus quantities were declining, this week there were even more samples with high concentration of coronavirus than two weeks ago. Lead researcher, Professor of Technology of Antimicrobial Compounds at the University of Tartu Tanel Tenson admitted that last week’s hope for an improvement in the situation was premature. “Virus quantities have grown everywhere in Estonia, and thus it is definitely reasonable to continue with current restrictions,” said Tenson.

Now also smaller places on the map of wastewater surveillance results

From this week, the map representing the results of the wastewater study also includes results of samples taken from smaller settlements. Differently from larger cities where the analyses reflect the average situation of wastewater that passes the treatment plant over 24 hours, in smaller places grab samples are taken, showing the amount of virus in wastewater at the moment of sampling.

“Grab samples are highly influenced by whether infected people have used the toilet around the time of sampling. Thus, it is necessary to monitor and compare the results from smaller communities over several weeks to assess whether the number of infections is growing or the outbreak is subsiding,” Tenson said. “In grab sampling, results confirming the presence of virus are probably reliable. However, a single grab sample with no virus may not always mean that there are no infections in the community,” he explained.

Wastewater samples are collected every week in all Estonian county centres, cities with more than 10,000 inhabitants and, if necessary, in smaller settlements. The study is a tool supporting the Health Board by providing early information to assess the spread of the virus before clinical cases are detected. The monitoring helps to find hidden outbreaks and monitor changes in the dynamics of outbreaks. The Health Board is regularly informed of the results.

When collecting the samples, the University of Tartu cooperates with the Estonian Environmental Research Centre and water companies operating the water treatment plants of Estonian cities. Wastewater 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,