Letter to the Editor: Wastewater-Based Epidemiology Can Overcome Representativeness and Stigma Issues Related to COVID-19.

We read with great interest the Viewpoint by Mao et al., “Can a Paper-Based Device Trace COVID-19 Sources with Wastewater-Based Epidemiology?”[1] We agree regarding the benefits of a wastewater-based epidemiology (WBE) approach in predicting the spread of the COVID-19 infection by analyzing the presence of the virus in wastewater. Concentrations of the norovirus in wastewater samples collected every week accurately reflect the infection in the watershed, suggesting that this approach can serve as a warning of a public outbreak.[2] We suggest additional advantages to this approach and call for a wastewater collection campaign involving international cooperation between environmental researchers, wastewater workers, and public health specialists, aimed at preventing the spread of COVID-19.

The WBE approach to testing for COVID-19 has potential advantages over testing the public. First, virus concentrations in wastewater represent the overall status of the watershed, while the number of COVID-19 cases involving infected people is possibly biased. Testing of the public seldom involves complete enumeration or even randomized sampling, because these sampling methods tend to overwhelm or collapse the medical care system, have the disadvantage of false-positives, and are time and labor intensive. The WBE approach is effective in identifying temporal changes in the infection status in the watershed without selection bias. Its second advantage relates to the issue of the stigma that can result from a COVID-19 outbreak. Infected people, or those diagnosed with a false-positive, together with their families, are potentially harmed by stigma and discrimination as well as social isolation.[3] This is one of the disadvantages of testing in complete enumeration or randomized sampling of the entire population. So far, WBE may not have been preferred due to potential regional stigma; however, WBE has proved its value by avoiding individual stigmatization. By contrast, in the current context of a worldwide outbreak of COVID-19, details of the number of cases in a particular region, and sometimes identifying details of infected individuals, are already being broadcast.

Detection of SARS-CoV-2 in urban wastewater has been reported in The Netherlands where RT-qPCR tests have been used,[4] although these tests still need more careful investigation regarding their sensitivity and specificity. The necessary analytical techniques must be developed, and in the meantime, wastewater samples should be collected and frozen regularly for future validation of the method and reconstruction of the temporal trends of the infection. Meeting this challenge could provide a perspective on preventing the continuing spread of the COVID-19 pandemic.