COVID-19 Testing at the Community Level – Digital PCR is a Key Tool
This month marked the anniversary of the World Health Organization’s declaration of the SARS-CoV-2 outbreak as a pandemic. Virtually all aspects of normal life and business were quickly disrupted by the novel and deadly coronavirus as it spread across the world. But researchers and the analytical instrumentation companies that supply them rose to the occasion.
Among the greatest challenges faced by epidemiologists and governments of all levels was accurately gauging the prevalence of COVID-19 to track the transmission of the disease within communities. This was information vital to the strategic effort to combat the spread of the virus, even if regional approaches drastically varied. But even in communities where PCR-based testing for COVID-19 infection was more widely available, the asymptomatic nature of a large portion of cases made it difficult to accurately determine infection rates. To better understand the prevalence of the disease, some governments and epidemiologists looked for clues from a communal source: sewage. When direct testing of the population was not possible or impractical, wastewater surveillance could provide indirect, but fairly accurate, measurements of the spread of COVID-19.
Several testing methods are available to quantify SARS-CoV-2 RNA present in wastewater. The Centers for Disease Control has published guidelines for wastewater surveillance in the US, recommending the use of either reverse transcription-quantitative PCR (RT-qPCR) or reverse transcription-droplet digital PCR (RT-ddPCR), a specific method within digital PCR (dPCR). RT-ddPCR has emerged as the preferred method, as it offers several advantages over RT-qPCR. While both methods are sensitive to low abundance RNA, RT-ddPCR offers higher sensitivity while also facilitating the absolute quantification of nucleic acids, as opposed to the relative abundance measurements that are achieved by RT-qPCR. ddPCR is also less sensitive to the presence of inhibitors which may influence the amplification reaction. Further, a recently published study has shown that RT-ddPCR is capable of accurately quantifying SARS-CoV-2 viral load from crude lysate, eliminating the need for nucleic acid extraction prior to analysis.
Wastewater testing was an unexpected driver of demand for dPCR
Wastewater testing was an unexpected driver of demand for dPCR in 2020, making dPCR one of the few non-diagnostic technologies to experience strong growth in a year marked by severe disruption. Even as the global response to the pandemic shifts away from diagnostics and monitoring to focus on mass vaccination of the population, surveillance of wastewater will remain important, as the emergence of vaccine-resistant SARS-CoV-2 variants is a serious possibility. Demand from continuing monitoring efforts will bolster recovering demand from non-COVID-19-related research and development.
The market for digital PCR is examined in the recently published SDi Global Assessment Report 2021, which takes a comprehensive look at dPCR in the context of the wider PCR market to provide data on market size, vendor share, and forecasts by product type, region, end market, and application. Along with PCR, the report examines 83 individual instrumentation and equipment technologies, organized into 10 major categories, making the Global Assessment Report the definitive reference tool for the analytical and life science instrumentation industry.