Waste water analysis predicts a rise in infections in northern Estonia

This week’s results of the waste water analysis led by the University of Tartu show an increase in coronavirus levels. Compared to previous weeks, the rise has been the most significant in Harju County. Pärnu and Lääne County have also experienced a slight increase in coronavirus levels. Hiiumaa continues to be free from the virus.

The data from the three past weeks shows that the number of places with a very wide spread of the virus has kept growing. At the same time, there are fewer and fewer places with low levels of the virus. According to the lead researcher of the study, Professor of Technology of Antimicrobial Compounds of the University of Tartu Tanel Tenson, we can no longer say that the situation remains stable. “While this week, the infection rate has increased in central Estonia, our data indicates that the next increase can be expected in northern Estonia. The virus concentration in Harju County was twice the Estonian average. The situation in southern Estonia is not likely to improve, either, as the virus levels continue to be significantly above the Estonian average,” Tenson explained.

How are the samples collected?

Waste water 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 waste water passing through the treatment plant over 24 hours, giving a reliable overview of the infection level in the city. The spot samples taken in smaller places show the situation at the moment of sampling. Spot samples are more easily affected by various factors and should therefore be used in comparison 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 the collection of samples, the University of Tartu cooperates with the Estonian Environmental Research Centre and water companies operating the 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”.

Further information: Tanel Tenson, Professor of Technology of Antimicrobial Compounds of the University of Tartu, 5344 5202, tanel.tenson@ut.ee