Predicting the number of people infected with SARS-COV-2 in a population using statistical models based on wastewater viral load

The quantification of the SARS-CoV-2 RNA load in wastewater has emerged as a useful tool to monitor COVID-19 outbreaks in the community. This approach was implemented in the metropolitan area of A Coruña (NW Spain), where wastewater from a treatment plant was analyzed to track the epidemic dynamics in a population of 369,098 inhabitants. Statistical regression models from the viral load detected in the wastewater and the epidemiological data from A Coruña health system that allowed us to estimate the number of infected people, including symptomatic and asymptomatic individuals, with reliability close to 90%, were developed. These models can help to understand the real magnitude of the epidemic in a population at any given time and can be used as an effective early warning tool for predicting outbreaks. The methodology of the present work could be used to develop a similar wastewater-based epidemiological model to track the evolution of the COVID-19 epidemic anywhere in the world. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Authors would like to give special thanks to the Board of Directors from EDAR Bens. Also, we would like to thank Fernanda Rodriguez from the Research Support Services (SAI) at the University of A Coruna, Laura Larriba, from SERGAS, who helped in samples and data collection in CHUAC, Francisco Perez, Javier Fernandez and Cristina Rodriguez from Cadaqua, for their help in sample collection at WWTP Bens, Andres Paz-Ares and Xurxo Hervada, from SERGAS, who provided the anonymized patient database, Amalia Jacome, Ana Lopez-Cheda, Rebeca Pelaez and Wende Safari, from CITIC at UDC, who processed that database to produce the epidemiological series at the municipality level, and Fiona Veira McTiernan, for editing. Finally, we would like to acknowledge the NORMAN European Network for Collaboration in the time of Covid19. This work was supported by EDAR Bens S.A., A Coruna, Spain [grant number INV04020 to MP], the National Plan for Scientific Research, Development and Technological Innovation 2013-2016 funded by the ISCIII, Spain - General Subdirection of Assessment and Promotion of the Research-European Regional Development Fund (FEDER) A way of making Europe [grant numbers PI15/00860 to GB and PI17/01482 to MP], the GAIN, Xunta de Galicia, Spain [grant number IN607A 2016/22 to GB, ED431C-2016/015 and ED431C-2020/14 to RC, ED431C 2017/58 to SL, ED431G 2019/01 to RC and SL, and ED431C 2017/66 to MCV], MINECO, Spain [grant number MTM2017-82724-R to RC], the Spanish Network for Research in Infectious Diseases [REIPI RD16/0016/006 to GB]. The work was also supported by the European Virus Archive Global (EVA-GLOBAL) project that has received funding from the European Union Horizon 2020 research and innovation program under grant agreement No 871029. SR-F was financially supported by REIPI RD16/0016/006, KC-P by IN607A 2016/22 and the Spanish Association against Cancer (AECC) and JAV by IN607A 2016/22. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Authors confirm that it was not necessary to certify the approval of the ethics committee to carry out this work. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The authors declare that all data supporting the findings of this study are available within the article and Supplementary Information files, and also are available from the corresponding authors on reasonable request.