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

Abstract

The study analyses SARS-CoV-2 presence and evolution on the sewage sanitation system in Madrid region as a tool for early warning detection of SARS-CoV-2 spreading from wastewater-based epidemiology approach. A total of 289 sampling points is weekly characterised in terms of SARS-CoV-2 concentration that collect over sin million and half inhabitansts' discharges. The project is developed by Canal de Isabel II, the water utility from Madrid. The research evaluates the correlation found between SARS-CoV-2 concentration in wastewater and public health indicators which are incidence rate, reported active cases and COVID-19 hospitalization data. Up to two points are sampled weekly. SARS-CoV-2 presence and evolution in wastewater show a strong connection with both 14-day incidence rates with active infection and reported COVID-19 hospitalisations. A lag varying from 3 to 8 days between wastewater presence and hospitalisations is explained because the infection is found in faeces of patients before symptom onset. Values are available for consultancy on the company’s website. Results have already been useful to anticipate to the second and third waves in Madrid. Information is daily shared with Health authorities for consultancy and decision-making. Results are available as an aggregation for the entire region and for each sewershed. Funding Statement: The project has been financed with own investment of the Canal de Isabel II Company amounting to approximately three million euros. Declaration of Interests: AL, JB, AP, JS, JIU, PF and MO work at Canal de Isabel II. FJC work part-time as advisor to the Ministry of Public Health in the Community of Madrid. JC is assistant to the Vice-counselor of public health in the Community of Madrid. AZ is the Vice-counselor of Public Health in the Community of Madrid.