Potential and Challenges Encountered in the Application of Wastewater-Based Epidemiology as an Early Warning System for COVID-19 Infections in South Africa

Abstract

The use of wastewater-based epidemiology (WBE) as a disease surveillance tool during the COVID-19 pandemic has been mainly to achieve two goals: early warning and determining changes in infection numbers over time. This study focused on the utilization of WBE as an early warning tool for COVID-19 infection in the eThekwini municipality of South Africa. Four wastewater treatment plants treating mainly domestic wastewater were chosen for this study. A central wastewater treatment plant was first used to determine the early warning potential of WBE, and thereafter, the tool was applied at three other locations. Viral concentrations in the raw wastewater were determined via the droplet digital polymerase chain reaction (PCR) method. The SARS-CoV-2 concentration varied from 4 to 7 Log10/100 mL of raw wastewater during the study period. The changes in viral concentration corresponded with the active COVID-19 cases within the study area. As an early warning tool, the WBE data was able to detect increasing infections in the community at least 5 weeks prior to increasing clinical cases during the third wave of COVID-19 infections in the country. Similarly, SARS-CoV-2 concentrations began increasing on November 30, 2021 prior to an increase in clinical cases on December 14, 2021, giving an almost a 2 week lead time. However, statistically, a 2–3 week lead time was determined to show the highest relationship with increasing COVID-19 cases. This study therefore identified the lead time as being between 2 and 3 weeks for early warning of COVID-19 infections using WBE data. Application of the early warning system at the three other catchments during the fourth wave of COVID-19 infections gave similar results of a lead time of 2 weeks. Therefore, the findings in this study further support the use of WBE as an early warning system. However, further studies are still required to address the challenges hindering the accurate and efficient use of this tool.