Should Septic Tanks Be Emptied Frequently to Prevent COVID-19 Variants? [Reading Science]

US UCSD Research Team Develops New Testing Method... Detects Variants Beyond Original Strain
Recent Variants Found in Sewage Weeks Before Human Detection
Potential 'Game Changer' for Early Warning and Strengthened Quarantine Measures

Photo by Getty Images.

[Asia Economy Reporter Kim Bongsu] Recently, new variants of the COVID-19 virus with increased transmissibility have continued to emerge, raising concerns about another wave of resurgence. Amid this, a study has found that COVID-19 variants are detected in wastewater weeks before they are found in humans. This suggests the potential use of wastewater surveillance for early warning and establishing quarantine systems against variant spread.

According to the international journal Nature on the 9th, a microbiology research team at the University of California San Diego (UCSD) announced these findings on the 7th.

Researchers worldwide have previously collected and tested samples from septic tanks and wastewater to investigate the presence and community spread of the COVID-19 virus. However, due to the nature of the samples, many were degraded, making it difficult to apply these methods to variant viruses.

To overcome this, the research team developed a method using nanobeads to increase the amount of intact viral RNA extracted from wastewater samples, enabling precise testing. Previously, less than 40% of viral RNA in samples could be used for testing, but with nanobeads, this was increased to 95%. They also developed a tool called Rreyja to track the types and proportions of variants present in each sample.

To validate this method, the team collected and tested wastewater samples from the San Diego area, with a population of about 2.3 million, for approximately one year starting in February last year. They also collected wastewater from about 130 locations on their campus over 10 months.

The results confirmed that the Alpha and Delta variants began to appear in wastewater up to two weeks before being detected in people. The Omicron variant was also detected in wastewater about 10 days before the first patient appeared in the San Diego area.

Notably, the team found that other variants such as Alpha, Delta, and Epsilon, which were almost undetectable in human testing over the past year and thought to have disappeared, continued to be present in wastewater samples. However, it has not yet been confirmed whether the method developed by the team is effective for recent variants like Omicron BA.4 or BA.5, which are currently driving the resurgence.

Rob Knight, a UCSD researcher and co-author of the study, explained, "If this research is further developed, it could enable faster tracking of viral variants, accelerating public health responses and preparing for virus resurgence."

However, there is still the challenge of reducing the current two-week turnaround time from sample collection to results. Professor Phong Thai from the University of Queensland, Australia, pointed out to Nature, "To be a useful tool for early warning systems, sample testing results need to be obtained within a few days."

Researcher Knight also said, "We are working to reduce the sample testing time to within a few days, and if achieved, it could be a 'game changer.'"