How to Anticipate Public Health Indicators Using Wastewater SARS-CoV-2 Concentration During the COVID-19 Pandemic. Madrid Region Case Study

Abstract This study analyzes the presence and dynamics of SARS-CoV-2 in sewage sanitation systems in the Madrid region. The statistical results and data generated are presented daily via a platform as a tool for the early detection of SARS-CoV-2 and its spread based on the WBE (wastewater-based epidemiological) approach. The number of sampled points amounts to a total of 289 sampling points in terms of SARS-CoV-2 concentration that collects over six million and a half inhabitants’ discharges. The project was developed by Canal de Isabel II, the water utility company from Madrid. The research evaluates the correlation found between SARS-CoV-2 concentration in wastewater and the following public health indicators: incidence rate, reported active cases and COVID-19 hospitalization data (regular hospitalization and ICU admission cases).SARS-CoV-2 presence and dynamics in wastewater show a strong connection with both 14-day incidence rates with active infection and reported COVID-19 hospitalizations. A lag varying from 3 to 8 days between wastewater presence and hospitalizations is explained because the infection is found in the feces of patients before symptom onset. The resulting data are available for consultancy on the company’s website (named VIGÍA project) as well as on the regional government’s websites.The results have already been useful to anticipate the second and third COVID-19 waves in Madrid. Information is shared daily with health authorities for consultancy and decision-making. The results are available as an aggregation for the entire region and for each sewershed.