SARS-CoV-2 Titers in Wastewater Are Higher than Expected from Clinically Confirmed Cases

Will the extraction of COVID-19 from wastewater help flatten the curve?

With the potentially fatal effect of COVID-19 and its devastating impact on economies worldwide, some environmental scientist has suggested the use of waste from household sewage to trace the movement of SARS-CoV-2, within a given country. However, this approach is not without challenges where developing countries lack proper and adequate hygiene and sanitation, resulting in widespread defecation. Limited scientific research has been done to determine how many times a recently infected person can defecate and the quantification of SARS-CoV-2 found in a single expel. On the other hand, there is no detailed research to specify where the heavy viral load of SARS-CoV-2 can be found in human excreta. In this paper, we present some obstacles that this approach could face in the absence of an intense lockdown in developing nations such as sub-Saharan countries. To achieve this, we identify some research needs that will strengthen our understanding of the transmission, occurrence, and persistence of SARS-CoV-2 in sewage and wastewater, including the life-span that depends on temperature. A methodology to follow in the process of identifying a hotspot on a small scale using some mathematical distributions, including the normal distribution, log-normal distribution, and the most complex one known as Blancmange function, was presented with some examples. Our investigation showed that this method might have some challenges, especially in developing countries (sub-Sahara countries) where open latrine usage is very high. Some recommendations we suggested to ensure the efficiency of such a method on a small scale. However, in general, it is essential to note the extraction/detection method will not help more than the testing method used all over the world to trace SARS-CoV-2 -19 in humans.

Wastewater-Based Epidemiology to monitor COVID-19 outbreak: Present and future diagnostic methods to be in your radar

The WHO has declared the COVID-19 epidemic on January 31, 2020. This virus has infected millions of people worldwide in just a few months. Shortly afterwards, the National Medical Products Administration (NMPA) announced nucleic acid testing as the gold standard for virus detection. Antibody testing is used as well as a supplementary test for suspected cases where nucleic acid detection was negative. In short, nucleic acid-based polymerase chain reaction (PCR) is the mainstream detection method for clinical samples as well as for the detection of SARS-CoV-2 in wastewaters. First data collected around the globe were reported in the last few months being part of the so-called Wastewater-Based Epidemiology (WBE) approach. Selection of concentration methods and primers, laboratory inter-comparison and various modalities of PCR detection of the virus in complex wastewater matrices were flagged up as main bullets that require urgent improvement. Novel approaches to enhance sensitivity, speed and automate streamlined virus detection will be discussed here as well. This list comprises devices mainly used for clinical purposes like Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), Digital PCR, Lab-on-a-chip (LOC) and related platforms as well as Biosensors. The last part will be devoted to the identification of biomolecules to target Covid-19 outbreak based on inflammatory response biomarkers among others. To this end this opinion paper brings for discussion the issue of PCR detection and its limitations as well as new diagnostic methods in WBE.