A study published in AACC’s Clinical Chemistry journal shows that a new protocol for coronavirus testing can increase clinical labs’ testing capacity without sacrificing accuracy. This protocol could play a vital role in helping labs keep up with coronavirus testing demands as the Delta variant fuels a new increase in COVID-19 cases around the world.
Due to the highly transmissible Delta coronavirus variant, global COVID-19 cases have gone up 12% during the week of July 11-18, and the average of new daily cases in the U.S. in particular has surged by 145% over the past two weeks (July 5-18). Making matters worse, vaccination coverage continues to lag. Many resource-limited countries are still struggling to secure coronavirus vaccines, while, in the U.S., vaccine hesitancy is hindering efforts to achieve herd immunity. More than half of the U.S. population is unvaccinated and highly likely to remain that way, according to a recent poll published by Axios-Ipsos. All of this means that PCR coronavirus tests—the gold-standard for diagnosing COVID-19—will continue to play a central role in managing the pandemic for the foreseeable future. It also means that, with the pandemic in this new growth phase, the supply shortages that stymied testing for the first year of the pandemic must be prevented from reoccurring.
Streamlined Testing Protocol
To support this goal, a team of researchers led by Lea Starita, PhD, and Christina Lockwood, PhD, of the University of Washington has developed a new, streamlined protocol for PCR coronavirus testing called SwabExpress. Typically, PCR coronavirus testing involves the extraction of viral genetic material from nasopharyngeal patient specimens transported in viral media. However, overreliance on this protocol throughout much of the pandemic contributed to a global shortage of extraction reagents, nasopharyngeal swabs, and viral media that hindered coronavirus testing even as recently as spring of 2021. SwabExpress, on the other hand, does not require viral media or extraction reagents, and also uses less invasive anterior nasal dry-swabs instead of nasopharyngeal swabs. All of this makes it ideal for averting future supply shortages and/or for use during periods of severe shortages.
In general, SwabExpress is much easier to perform than the standard PCR coronavirus testing protocol. After adopting SwabExpress, Starita and Lockwood’s laboratory approximately doubled its capacity for coronavirus testing. Importantly, unlike other extraction-free methods for nasal swabs that have been developed, SwabExpress is also highly accurate. The researchers demonstrated that it has a sensitivity of 100% and a specificity of 99.4% when compared side-by-side with a traditional PCR protocol.
“Massive scaling and deployment of SARS-CoV-2 testing is essential to curtailing the COVID-19 pandemic, and will likely be necessary well into the future,” says Starita and Lockwood. “The protocol evaluated here, including thousands of real-world, self-collected nasal swabs, would markedly simplify the workflow for RT-qPCR, the most widely deployed testing paradigm, by eliminating the need for viral transport media and RNA extraction. It may serve as a template for the simplification of PCR-based clinical laboratory tests, particularly in times of critical shortages during pandemics.”