Jan. 19 (UPI) -- New research suggests viral genome sequencing of wastewater can be used to identify new COVID-19 variants before they're picked up via other screening methods.
In Britain, scientists have been regularly sequencing the DNA of hundreds of COVID-19 samples on a weekly basis.
Since Britain's Covid-19 Genomics Consortium was formed in the early weeks of the pandemic, the project has traced the genetic history of more than 150,000 viral samples.
Elsewhere in the world, genomic surveillance efforts remain limited. In the United States, for example, hospitals, county health departments and testing labs are already overwhelmed testing and treating patients, while also facilitating an unprecedented vaccination effort.
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However, the emergence of what scientists suspect to be more contagious variants of the COVID-19 virus have health officials looking for new ways to track the spread of important viral mutations.
As detailed in a new paper, published Tuesday in the journal mBio, researchers at the University of California-Berkeley have developed a new technique for isolating unique viral strains amidst the millions other microbes.
"The way that we need to process the sequence information is complex. One contribution of this paper is the ability to prepare samples for sequencing from wastewater," lead researcher Kara Nelson, professor of civil and environmental at Berkeley, said in a news release.
"Instead of directly sequencing everything present, we used an enrichment approach where you first try to enrich the RNA that you are interested in. Then we developed a novel bioinformatic analysis approach which was sensitive enough to detect a single nucleotide difference. You can't get any more sensitive than that," Nelson said.
For the study, researchers sequenced the genes of different COVID-19 mutations in San Francisco wastewater. The analysis revealed levels of the most common COVID-19 variants similar to those identified by clinical sequencing efforts.
Additionally, researchers were able to identify the presence of specific COVID-19 variants that have been found in other parts of the United States but not yet found locally.
Scientists hope the new sequencing method can be used by health officials to track to spread of variants like B.1.1.7, the more contagious variant that has spread rapidly across Britain in recent months.
"Of everyone who gets tested, only a fraction of those samples even get sequenced. When you are sampling the wastewater, you get a more comprehensive and less biased data on your population," Nelson said.
"It appears that we might be able to get an earlier signal in the wastewater if a new variant shows up compared to only relying on the sequencing of clinical samples. Just knowing that [COVID-19] is present in a population is the first step in providing information to help control the spread of the virus, but knowing which variants are present provides additional but very useful information," Nelson said.
