The chart with data from the weekly analysis of the wastewater of Sofia for Covid-19 correlates with the official morbidity statistics. The results are a proof of the accuracy of the method developed by Sofiyska Voda, operated by Veolia, and the Center of Competence “Clean & Circle” of the Faculty of Biology with Sofia University “St. Kliment Ohridski”. 

Data shows that as at April 26, 435 gene copies/mgN of the virus at the inlet of the wastewater treatment plant near Kubratovo have been discovered. For the same day the Unified Information Portal reports 377 newly diagnosed people with COVID-19*. Gene copies represent the gene number of Covid-19 viral RNA and indicate the water pollution at the plant inlet. At present, tests are performed once a week on wastewater samples before the treatment process. 
We would like to remind that after a year of joint efforts, Sofiyska Voda and “Clean & Circle” developed the method following the example of a number of countries where Veolia Group operates. Similar to cities in France, Germany, Austria and Greece, Sofia may already determine the morbidity rates not only against clinical test data, but also according to domestic wastewater. 

The main advantage of the method is that it may serve to predict potential new waves and detect disease outbreaks, as the presence of the virus in wastewater comes ahead of the population’s exhibiting symptoms. The method may be used also for control purposes – if the test of the local population is negative, but the virus has been discovered in the wastewater, potential sources of infection must be examined. 

* Gene copy number does not measure the exact number of infected people, but a tendency towards increase or decrease of the virus in wastewater.