A team of researchers evaluated methods for monitoring COVID-19 infection trends through wastewater surveillance. They investigated wastewater data from Sapporo, spanning from April 2021 to September 2023, and found a strong link between the concentration of the virus in wastewater and the incidence of infections. The study highlighted several critical techniques, such as high-sensitivity analysis and geometric mean data processing, as vital for effective regional monitoring, offering important insights for future public health strategies.
Wastewater surveillance has emerged as a promising approach for tracking infection trends in specific areas. In July 2024, the National Action Plan for Novel Influenza and other diseases announced the routine application of wastewater surveillance even during ordinary periods, with results to be released on a regular basis across Japan. However, if the measurements of viral concentrations in wastewater are inaccurate or significantly fluctuate, the link to actual infection trends may diminish. This research pinpointed the essential methods needed for precise monitoring of COVID-19 infection patterns.
The researchers examined wastewater samples from Sapporo, Japan, collected over two and a half years, specifically from April 2021 to September 2023. The data exhibit heightened sensitivity (100 times more sensitive than conventional methods) and high reproducibility (with a standard deviation less than 0.4 at log10 values), relying on a robust sample size of 15 samples each week, amounting to a total of 1,830 samples throughout the period. The correlation coefficient between the number of confirmed infections and the viral concentration in the wastewater was 0.87, demonstrating the effectiveness of this approach in monitoring regional infection trends. The researchers also recommended that an ideal survey frequency should include at least three samples each week, preferably five.
“While some individuals express concerns about fluctuations in virus concentrations, we are confident that appropriate survey methods can accurately reflect regional infection trends,” stated lead author Michio Murakami. “This study is important, as it provides a tangible example of effective wastewater surveillance, using COVID-19 as a prime case.”
The research outlines comprehensive guidance on wastewater surveillance techniques for tracking infection patterns, emphasizing data processing, analytical sensitivity, and survey frequency. As the implementation of wastewater surveillance during regular times becomes more prevalent and results are more frequently published, the insights from this study are anticipated to be valuable for decision-making processes.
The article, titled “Evaluating survey techniques in wastewater-based epidemiology for accurate COVID-19 incidence estimation,” was published in Science of the Total Environment.
