SARS-CoV-2 concentration in wastewater and waves of contagion during the pandemic

Wastewater-based epidemiology has proven to be a very useful tool for monitoring the spread patterns of the SARS-CoV-2 coronavirus during the COVID-19 pandemic. However, few quantitative models have been established comparing virus concentrations in wastewater samples and cumulative incidence.

A new study fills this gap, for the specific case of the use of wastewater for the prediction of the incidence of SARS-CoV-2 in Catalonia. The authors of the study examined the relationship between the concentration of the SARS-CoV-2 coronavirus in wastewater and the cumulative incidence in the different waves of contagion during the pandemic, using a mathematical model.

Establishing a numerical relationship allows knowing, through a sample of drainage water and its analysis, what is the number of infected people in a defined territory. Thus, the mathematical model developed makes it possible to relate the concentration of viruses at the entrance of a treatment plant with the cumulative incidence reported in the hospitals of the corresponding territory during a wave of infections. The same model has been used to make short-term forecasts as the wave of infections progresses and has been compared with a local linear model.

Both scenarios have been tested using a dataset of samples from 32 wastewater treatment plants and severe acute respiratory syndrome 2 (SARS-CoV-2) incidence data covering the corresponding geographic areas over a 7-month period, including two waves of contagion.

The monitoring of the pandemic and the need to predict its spread required many logistical resources to be devoted to the work around the world. An example of this was the intense activity carried out in this American center (EOC, dependent on the CDC) to guarantee adequate coordination between the World Health Organization (WHO) and the federal, state and local medical organizations of that nation . (Photo: James Gathany/CDC)

Clara Prats, Daniel López-Codina, Enric Álvarez-Lacalle and Sergio Alonso, researchers from the Computational Biology and Complex Systems (BIOCOM) research group at the Polytechnic University of Catalonia (UPC), participated in the study; Martí Català, from the Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences, at the University of Oxford, United Kingdom; and Bernat Joseph Duran, Albert Serra Compte, Miquel Sàrrias, Susana González and Marina Arnaldos from Cetaqua, the Water Technology Center.

According to Bernat Joseph Duran, project manager of the digital area at Cetaqua, “the mathematical model based on wastewater data has shown a good correlation with the accumulated cases and has allowed us to anticipate the incidence of SARS-CoV-2 in a week. , which is especially relevant in situations where the epidemiological surveillance system cannot be fully applied”.

Clara Prats, a researcher in the research group at BIOCOM, adds: “we have shown that quantitative epidemiological surveillance can be carried out from the analysis of wastewater, a viable and interesting proposal. The collaborative work with Cetaqua has been a privilege for us: in research, public-private collaboration is essential!”

A collaboration that has been especially useful for the experience in mathematical epidemiology of the UPC and the knowledge and experience in the management of the integral water cycle and the persistence of the virus in the Cetaqua sewage network. The study has been carried out with the data provided by the Catalan Institute for Water Research (ICRA) and the Generalitat de Catalunya.

The study is titled “Assessing wastewater-based epidemiology for the prediction of SARS-CoV-2 incidence in Catalonia”. And it has been published in the academic journal Scientific Reports. (Source: UPC)