Incomplete sanitation in the Metropolitan Region of São Paulo results in detection of SARS-CoV-2 in headwater streams.

Among the largest metropolitan regions in the world, the Metropolitan Region of São Paulo (MRSP) represents an important case study for the COVID-19 respiratory disease pandemic because it is home to >20 million people, making it one of the largest metropolitan regions in the global south. Besides the high population density, the MRSP has several problems related to social and economic aspects, which may reflect in the dynamics of SARS-CoV-2 virus, such as low income, lack of sanitation and social vulnerability in the peripheral regions of MRSP. In these regions, the input of untreated sewage on the streams and rivers can be frequently observed, which may represent an indicator of poor sewer system.