Learn more about COVID-19 wastewater testing

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Wastewater-based epidemiology indirectly monitors infection rates in a community based on pathogen levels in local wastewater. Because symptomatic and asymptomatic SARS-CoV-2 infected individuals shed viral RNA in sewer systems, analysis of SARS-CoV-2 in sewage networks can provide information about SARS-CoV-2 infections within the community. However, the accuracy of these data depends on the quality of the wastewater testing method. During the COVID-19 pandemic, Droplet Digital PCR has proven that it has the sensitivity needed to detect outbreaks and monitor SARS-CoV-2 variants in communities via wastewater testing.

COVID-19 Poses Persistent Public Health Challenges

Novel variants of SARS‑CoV‑2 continue to emerge and spread.
 
Identifying asymptomatic individuals remains a challenge.
 
Sensitivity, accuracy, and time-to-results are lacking for some detection methods.

ddPCR Testing for Wastewater Surveillance

ddPCR technology uses a water-emulsion droplet system to partition nucleic acid samples and perform PCR amplification within each droplet. Droplet Digital PCR can be used to detect SARS-CoV-2 viral RNA shed in wastewater, providing real-time surveillance of spread at the community level. In a recent study, fluctuations in SARS-CoV-2 wastewater measurements predicted increases in confirmed case numbers in the area (Gonzalez et al. 2020).

Key Droplet Digital PCR facts:


We can be confident in our detection with Droplet Digital PCR technology — we know each test will be a true positive or negative.Walter Betancourt, PhD, Assistant Research Professor, University of Arizona

The ddPCR Workflow

Droplet Digital PCR is a 1-step process where reverse transcription and PCR are performed on individual droplets in the same reaction mixture. This process is considered advantageous because it can reduce inhibition of reverse transcription, in comparison to bulk methods.

7 Benefits of ddPCR Technology for Wastewater Surveillance

1

Faster Result

Assays using Droplet Digital PCR enable scientists to detect SARS-CoV-2 six days before clinical testing (Medema et al. 2020).

2

More Sensitive Results

Partitioning allows for enrichment of rare targets.

Detects 1 infected individual in 10,000
(Hart and Halden, 2020)

3

Absolute Quantification

Directly count DNA molecules and eliminate standard curves.

Inhibitor Tolerance

Endpoint PCR uncouples quantification from amplification and efficiency.

5

Variant Identification

Assays using Droplet Digital PCR can accurately discriminate and quantify multiple variants in a sample using a single-well test.

6

Cost Efficacy

Smaller sample requirements drive down cost.

7

Stability of Assay Design

Bio-Rad’s ddPCR Assays are designed to measure genes that are less mutated and more stable as amplification regions.

SARS-CoV-2 vials

The PREvalence ddPCR SARS-CoV-2 Wastewater Quantification Kit measures the SARS-CoV-2 E and N2 genes and includes an assay for Murine Hepatitis Virus (MHV), a murine coronavirus. The test allows for all three targets to be detected in a single well.


We chose ddPCR testing for our wastewater surveillance because it’s particularly resistant to inhibition, gives absolute quantification, and is more sensitive than other methods.Carol Wilusz, PhD, Professor, Colorado State University

Industries that May Benefit from ddPCR Surveillance

Colleges and Universities
 
Air Travel
 
Health Departments
and Municipalities

Learn More about Droplet Digital PCR and Wastewater Surveillance

Watch the Webinar

Hear about scientists’ experiences building a successful wastewater surveillance system at Colorado State University.

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References

Gonzalez R et al. (2020). COVID-19 surveillance in Southeastern Virginia using wastewater-based epidemiology. Water Res 186, 116296.

Hart OE and Halden RU (2020). Computational analysis of SARS-CoV-2/COVID-19 surveillance by wastewater-based epidemiology locally and globally: Feasibility, economy, opportunities and challenges. Sci Total Environ 730, 138875.

Jahne MA et al. (2019). Droplet digital PCR quantification of norovirus and adenovirus in decentralized wastewater and graywater collections: Implications for onsite reuse. Water Res 169, 115213.

Medema G et al. (2020). Presence of SARS-Coronavirus-2 RNA in sewage and correlation with reported COVID-19 prevalence in the early stages of the epidemic in the Netherlands. Environ Sci Technol Lett 7, 511–516.

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