Variant of Usual PCR May Speed COVID-19 Testing

By Reuters Staff

September 29, 2020

(Reuters) - Researchers say a variation of the gold standard polymerase chain reaction (PCR) test for diagnosing COVID-19 removes unnecessary steps and allows faster and less expensive testing, with at least equal accuracy.

"Digital droplet" PCR (ddPCR), an established technique, can effectively identify SARS-CoV-2 genetic material using unprocessed cells without any purification steps, the research team from the University of California San Francisco reported on medRxiv ahead of peer review.

The goal of PCR is to look for RNA and DNA, the genetic material in the virus. Normally, in a version of the test known as quantitative PCR (qPCR), all the materials are mixed together in a single large test tube, but the results could be affected by contaminating substances such as nasal cavity contents obtained during a swab for COVID-19 testing. To get around this problem, most qPCR tests are preceded by a purification step to remove contaminating substances.

By making it possible to bypass the RNA extraction step, ddPCR may help ease the coronavirus testing bottlenecks caused by shortages of the extraction chemicals as well as speed the delivery of results to patients, the researchers said.

SOURCE: medRxiv, online September 3, 2020.