Results

Phase 3 – Demonstration of the concept of early epidemiological warning of the increase or decrease in the concentration of SARS-CoV-2 and its circulating variants in untreated wastewater and the correlation of the results with clinical data (January 1, 2024 to December 31, 2024)

Summary of the stage

The WARNING project was designed to implement the monitoring of SARS-CoV-2 in untreated wastewater from two different locations in Bucharest: Glina Wastewater Treatment Plant (WWTP) and Clinical Hospital of Infectious and Tropical Diseases “Dr. Victor Babes” (H), for a period of at least one year (week 42/2022 – week 48/2023). In total, over 300 samples were collected (104 samples of composite untreated urban wastewater; 104 samples of current untreated urban wastewater; 103 samples of current untreated wastewater from the hospital). According to the data presented in the previous step, the raw data show a general trend, with a higher concentration of SARS-CoV-2 gc/ml in the hospital wastewater, followed by the sewage treatment plant samples by an order of magnitude difference. However, when the data were normalized to the population equivalent (e.g.), the concentration of SARS-CoV-2 gc/ml dropped drastically in the hospital (the data is normalized to the total number of hospitalized patients in the respective period), compared to the two WWTP samples, composite and momentary, which does not show a significant difference (data normalized to p.e.). The concentration of SARS-CoV-2 viral particles in untreated wastewater followed the incidence trend at 14 days per 100,000 inhabitants in Bucharest, noting that an increase in the concentration of SARS-CoV-2 RNA in wastewater is visible after approximately 2 weeks before being observed in officially reported clinical cases. Success in monitoring SARS-CoV-2 has stimulated interest in extending water-based surveillance (WBS) to other respiratory viruses, such as influenza A/B viruses (Flu A/B), parainfluenza viruses 1 / 2/ 3/ 4 (HPIV1/2/3/ 4), adenovirus (ADV), bocavirus (HBoV), respiratory syncytial virus (RSV A/B), human metapneumovirus (HMPV), enterovirus, rhinovirus (RV), parechovirus (PeV), and reovirus to identify a wide range of pathogens in wastewater, providing data valuable for disease prevention and control. ADV, HBoV, and reovirus were frequently detected both in the hospital and in the WWTP, the other viruses appearing only occasionally during the analyzed period. The concept of Water-Based Surveillance (WBS) continues to evolve, making significant contributions to public health and infectious disease research.