A simplified approach to monitoring the COVID-19 epidemiologic situation using waste water analysis and its application in Russia

The number of registered cases of COVID-19 is increasing in the world, and some countries are reporting a second wave of the pandemic. Accurate and real time information about epidemiological situation is therefore urgently needed for managing decisions in the countries, regions and municipalities which are affected. Massive testing of viral presence in human saliva, a smear from the nose, nasopharynx and / or oropharynx, bronchial lavage water obtained by fibrobronchoscopy (bronchoalveolar lavage), as well as from (endo) tracheal, nasopharyngeal aspirate, sputum, biopsy or autopsy material of the lungs, whole blood, serum or antibodies presence in blood cannot give relevant information about the COVID-19 infection rate in the community since simultaneous testing of the whole community is not technically possible, the information obtained in testing of specific groups is retarded and, in addition, such testing is expensive. The alternative to mass testing of the population is the testing of wastewater that could contain SARS-CoV-2 particles originating from excreta. Such testing has several limitations connected with the particularities of the testing procedure. In the present study, a modified approach for detection of COVID-19 infection rate using wastewater analysis has been developed. The approach includes i) the creation of a calibration curve on the basis of the serial dilution of excreta collected from people who are infected with COVID-19 and ii) the analysis of wastewater samples and their serial dilutions but the approach excludes usage of concentration techniques before wastewater sample analysis as well as usage of external control in RT-PCR reactions for calculation of numbers of viral particles. The minimum infection rate that can be detected using this approach is 0.01%. The approach developed was used to investigate wastewater from eleven sewage inspection chambers in the city of Kazan (Russia). It was demonstrated that the average infection rate of people using these sewers was over 0.4% in July 2020.