Recent Technologies for the Determination of SARS-CoV-2 in Wastewater

The COVID-19 pandemic outbreak raised major concerns in public health globally, raising the crucial need for the development of methods to monitor the spread of COVID-19 in communities worldwide. Wastewater-based epidemiology (WBE) surveillance has been used as a novel tool to monitor outbreaks in communities because of its affordability and efficiency in tracking infectious contaminants. Unlike other means of public health tracking, wastewater is independent of individuals having accessibility to healthcare, doctor visits, or infection testing availability. Consequently, raising considerable awareness and complete tracking of infections, including COVID-19 at a community level. In WBE studies, polymerase chain reaction-based (PCR) techniques are referred to as the "gold-standard" method for detecting SARS-CoV-2 in many countries. Nevertheless, despite the extensive development of sensitive and selective PCR-based methods, these techniques have shown some limitations that hinder their application, such as the requirement of repeated heating and cooling cycles and analysis time of 3-4 h. The development of alternative techniques that do not rely on the same consumables as the conventionally employed methods, such as electrochemical biosensing, for detecting SARS-CoV-2 in environmental water samples offers favorable advantages such as improved turnaround times and portability. However, the currently employed techniques are highly focused on clinical applications than wastewater. This review focuses on the advantages and disadvantages associated with conventional and a novel alternative: electrochemical-bioreceptor-based technique for detecting SARS-CoV-2. In addition, highlights the broad use of these techniques in clinical applications than WBE, the binding affinity of the various bioreceptors toward SARS-CoV-2 viral proteins, and their use in enhancing the analytical properties of electrochemical biosensors and the integration of electrochemical biosensors with conventional techniques. The integrated systems, especially, electrochemical-CRISPR based, have shown high sensitivities (down to concentrations of atto-molar), with potential application in low-resource areas.