Metropolitan Wastewater Analysis for COVID-19 Epidemiological Surveillance

Background The COVID-19 disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a rapidly emerging pandemic which has enforced extreme containment measures worldwide. In the absence of a vaccine or efficient treatment, cost-effective epidemiological surveillance strategies are urgently needed. Methods Here, we have used RT-qPCR for SARS-CoV-2 detection in a series of longitudinal metropolitan wastewaters samples collected during the earliest stages of the epidemic in the Region of Valencia, Spain. Results We were able to consistently detect SARS-CoV-2 RNA in samples taken when communicated cases in that region were only incipient. We also find that the wastewater viral RNA context increased rapidly and anticipated the subsequent ascent in the number of declared cases. Interpretation Our results strongly suggest that the virus was undergoing community transmission earlier than previously believed, and show that wastewater analysis is a sensitive and cost-effective strategy for COVID-19 epidemiological surveillance. Routine implementation of this surveillance tool would significantly improve our preparedness against new or re-occurring viral outbreaks.