Long-Term Monitoring of SARS-COV-2 RNA in Wastewater in Brazil: A More Responsive and Economical Approach

SARS-CoV-2, the novel Coronavirus, was first detected in Wuhan, China, in December 2019, and has since spread rapidly, causing millions of deaths worldwide. As in most countries of the world, in Brazil, the consequences of the COVID-19 pandemic have been catastrophic. The increasing of deaths and the decrease of available beds in the hospitals, especially in 2021, have disturbed the health authorities. Several studies have reported the fecal shedding of SARS-CoV-2 RNA titers from infected symptomatic and asymptomatic individuals. Therefore, the quantification of SARS-CoV-2 in wastewater can be used to track the virus spread in a population via Wastewater-based Epidemiology (WBE). In this study, samples of untreated wastewater were collected weekly between June 9th, 2020 and March 17th, 2021 (41 weeks) at five sampling sites in the ABC Region, São Paulo, Brazil. This long-term monitoring was performed to evaluate the SARS-CoV-2 occurrence in the sewerage system. SARS-CoV-2 RNA titers were detected throughout the period. The viral RNA concentration ranged from 2.7 to 7.1 log10 genome copies.L− 1, with peaks in the last weeks of monitoring. Furthermore, we observed a positive correlation between the viral load in wastewater samples and the epidemiological/clinical data, with the former preceding the latter by approximately two weeks. The COVID-19 prevalence for each sampling site was estimated using the viral load observed in wastewater and other parameters, via Monte-Carlo simulation. The mean predicted prevalence ranged 0.05 to 0.38%, slightly higher than reported (0.016 ± 0.005%) in the ABC Region for the same period. These results highlight the viability of the WBE approach for COVID-19 infection monitoring in the largest urban agglomeration in South America. Environmental surveillance can be especially useful for health agencies and public decision-makers in predicting SARS-CoV-2 outbreaks, as well as in local tracing of infection clusters.