SARS-CoV-2 Detection in Wastewater using Droplet Digital PCR by Paul J. Parsons, Ph.D.

Before the COVID-19 pandemic, what was your primary role or field of research?

I work for a National Environmental Research Council (NERC) funded initiative known as NEOF — the NERC Environmental Omics Facility. It’s essentially an evolutionary and environmental genomics partnership between labs at the University of Sheffield and the University of Liverpool. We have many years of experience working with environmental samples using a variety of genetic and genomic tools including qPCR, metabarcoding and whole genome sequencing. My role was wide-reaching; supporting visitors with laboratory work and analysis, as well as performing my own research on a number of wildlife conservation projects.

How severely has your region been impacted by the pandemic?

Broadly speaking, the UK has been heavily impacted by the pandemic with 42,369 confirmed deaths as of October 6, 2020). The number of cases is rapidly increasing in our local catchment area of Yorkshire. Today, there with 286 cases for every 100,000 people — far more than we would like to see.

How did this wastewater project come about? Who seeded the idea and when?

The project came about in discussion with several other groups including Yorkshire Water, Sheffield COVID-19 Genomics Group, the University of Bangor, and our NEOF partners at Liverpool. We have since been incorporated into the National Wastewater Epidemiology Surveillance Programme, NWESP, a NERC-funded collaboration between 23 institutions looking into the presence and infectivity of COVID-19 in UK wastewater.

What was the primary goal? What did you hope to determine or achieve?

Our primary goal is to help. Through our work, we hope to get one step ahead of the virus by identifying potential outbreaks and areas for concern early on.

Why did you choose to use ddPCR technology to measure SARS-CoV-2? What Bio-Rad platforms did you use to achieve that?

We are using the QX200 Droplet Digital PCR System. We felt that using ddPCR may allow for greater accuracy and sensitivity when identifying presumably low abundant targets within our wastewater samples. It is also reported to be more robust when using samples with variable amounts of chemical and protein contaminants – which are highly likely to be present in wastewater.

What was the scope of the project — for example, how many people were in the wastewater catchment area?

Our local project currently involves seven sites across South Yorkshire, an area with a population of approx. 1.4 million people. We hope to increase the number of sites and potentially target new emerging areas of concern in the future. The NWESP collaboration study as a whole covers several sites across mainland Britain.

What were the key outcomes/findings from your project?

While the project is ongoing, we have so far successfully managed to track the virus over several sampling weeks and locations with a good level of repeatability.

How do you think wastewater testing using ddPCR might help stop the spread of SARS-CoV-2 in different communities?

Our work — especially the work we are doing in collaboration with NWESP on the national level — could provide vital information to help slow the spread of COVID-19. The wastewater data we generate could potentially be used as an early warning system to identify new outbreak locations. Those populations could be notified about their increased risk, while officials direct medical resources to hospitals likely to experience higher demand for COVID tests and treatments. We’re also capturing information around the extent and rate at which COVID-19 spreads within a population — including the difficult-to-identify segments of the population that remains asymptomatic. This could help inform future policy decisions and provide guidance on how all individuals, even those who don’t know they’re infected, can help to reduce the spread of the virus and effectively address outbreaks when they do happen.

Digital PCR

Bio-Rad's unique Droplet Digital PCR technology provides absolute quantification of nucleic acids for a wide range of applications including cancer mutation studies, HIV quantification, and environmental monitoring.

View ddPCR Products | Find Your ddPCR Assay