Waste water analysis shows the coronavirus is receding

This week’s results of the waste water analysis led by the University of Tartu show that the amount of coronavirus has notably decreased throughout Estonia since last week. The situation has also markedly improved in south-east Estonia.

The virus concentration has come down to a moderate level in the waste water samples taken from almost all larger settlements in Estonia. The situation has also improved considerably in Põlva and Tõrva, which stood out by high virus levels a week ago. However, no larger regions can be considered free from the virus yet. According to the lead researcher of the study, Professor of Technology of Antimicrobial Compounds of the University of Tartu Tanel Tenson, it is now quite safe to say that the third wave, mainly caused by the delta strain, is subsiding. “This is indicated by the fact that we can see a sharp fall in the virus concentrations across Estonia, both in larger and smaller settlements. The first signs of decreasing virus levels could be noted four weeks ago. It is possible that mass testing at schools that started around the same time played an important role in this, helping to limit the spread of the infection,” said Tenson. He also emphasised the importance of vaccination in curbing the spread of the virus.

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”.

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 of the University of Tartu, 5344 5202, tanel.tenson@ut.ee