Wastewater analysis supports observations of coronavirus incidence - the virus is still found across the country

Publication date 2 Feb 2021

In the latest extensive monitoring exercise on 24 and 25 January, the coronavirus genome was detected in a total of 26 samples from wastewater treatment plants. No coronavirus was detected in samples from Luotsinmäki plant in Pori and Hopeakivenlahti plant in Kokkola.

In the first extensive wastewater monitoring on 10 and 11 January, the coronavirus genome was found at all wastewater treatment plants where samples were collected, with the exception of Hopeakivenlahti in Kokkola. In total, samples from 28 waste water treatment plants are tested for the coronavirus over two-week monitoring periods.

The numbers of virus RNA copies follow the trend in infections

The total numbers of coronavirus RNA copies in samples collected at wastewater treatment plants are rather consistent with the incidence of coronavirus infections in Finland. These wastewater samples cover around 60 per cent of the Finnish population.

Graphic: The number of coronavirus RNA copies in wastewater follow the trend in COVID-19 incidence

"The observations of coronavirus detected in wastewater largely follow the case trend observed in individual testing. Depending on when the wastewater sample is collected, we have at times been able to detect an acceleration phase of the epidemic even before individual testing”, notes Tarja Pitkänen, Chief Specialist at THL.

The numbers of RNA copies at treatment plants vary substantially in different localities. The results may be affected by many quality factors of the sample, including its temperature and delays of waste water flow in the sewer network.

"When the results are totalled at the national level, the importance of an individual sample is reduced", says Pitkänen.

Results of coronavirus monitoring in wastewater on the map and retrospectively 

The Finnish Institute for Health and Welfare publishes its wastewater monitoring findings, which support the national situational picture of the coronavirus epidemic, on its website every week on Tuesdays. The more limited findings based on wastewater samples collected at treatment plants in Helsinki, Turku, Tampere, Kuopio and Oulu are published every two weeks.

The map shows the occurrence of the coronavirus over the last two weeks at the 28 monitored wastewater treatment plants. On the data tab of the weekly report, the findings at individual treatment plants from the beginning of August 2020 can be viewed.

Report of findings (map of coronavirus observations from two previous weeks, in Finnish)

Wastewater monitoring to support preparedness for pandemics 

Wastewater may provide more indicators for public health monitoring in the future. 

This development work is being carried out in the three-year WastPan project funded by the Academy of Finland, which began in November 2020. In this project, the Finnish Institute for Health and Welfare and the Universities of Tampere and Helsinki will develop wastewater monitoring into a tool which can be used to investigate the spread of pathogens and antibiotic resistance as well as prepare for pandemics.

More information 

Wastewater monitoring project site (in Finnish and Swedish)

Wastewater-based surveillance as a pandemic preparedness tool (WastPan)

Tarja Pitkänen
Chief Specialist
tel. +358 29 524 6315
[email protected]

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