Amount of coronavirus in wastewater continues to decrease

Coronavirus concentration in wastewater has decreased to a moderate level in many regions in Estonia. The number of samples with very high concentration has dropped by a third in a week.

The leader of the study, UT Professor of Technology of Antimicrobial Compounds Tanel Tenson says that although the amount of the virus has decreased in most places, the readings in the larger cities of Ida-Viru County still remain high. The concentration is also high in Tallinn and the Viimsi-Muuga area, Haapsalu, Pärnu, Tartu and in Võru County. According to Tenson, the current indicator is still comparable to the one at the beginning of February. “Considering that currently the level of new infections is relatively high, it still takes time before we can see a bigger change,” Tenson explained.

How and where are the samples collected?

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,