Wastewater-Based Epidemiology for Early Warning and Surveillance of Covid-19

Wastewater-based epidemiological has become a cost-effective complementary tool for community-level COVID-19 surveillance. This has become necessary due to the cost, turnaround time and possible underestimation of the severity of the infection associated with clinical-based surveillance. Furthermore, WBE has become widely used due to its ability to capture symptomatic, pre-symptomatic and asymptomatic carriers within communities. It therefore achieves a much more sensitive surveillance system, which helps in early warning and identification of infection hotspots. This chapter, therefore, highlights the main principles of WBE and its history so far. We also discuss the methodological approaches that have either been used or could be used for COVID-19 surveillance through WBE. The successful applications of this approach during this pandemic (COVID-19) are also presented to show the proof of concept for this surveillance system. We also present some of the challenges with the methods that have been used and how these can be enhanced to develop an effective WBE tool for COVID-19 surveillance. The reviewed literature highlighted some key methodological steps in WBE, these include sampling, either grab or composite sampling. Concentration of the samples to increase the sensitivity of the methods is also commonly applied. Additionally, several types of nucleic acid extraction and amplification techniques are currently used for the detection of SARS-CoV-2 from wastewater, the main principle behind WBE. Some of these amplification techniques include conventional polymerase chain reaction (PCR), real time PCR or the more advanced digital PCR. Furthermore, next-generation sequencing (NGS) has been applied for the identification of this virus in wastewater and even identifying the variant of the virus in circulation among the populations. Despite the utility of WBE as presented in this chapter, several other challenges have been identified and reported. The review of WBE as presented in this chapter therefore highlights the significant contribution this approach has made and continues to do toward improving surveillance of COVID-19.