Researchers at the University of Washington have developed a new COVID-19 test that has the speed of over-the-counter antigen tests and the accuracy of medical-grade PCR tests.

Dubbed the ‘Harmony’ test, this diagnostic tool looks for the genetic material of the SARS-CoV-2 virus in test samples. However, unlike PCR tests, which can take several hours to produce a result, the Harmony kit can provide a diagnosis in under 20 minutes with high accuracy.

The test was designed to be low-cost and straightforward to use, according to the authors, in a bid to help everyone, from doctors to the public, to better detect and track coronavirus infections.

New tools

“We designed the test to be low-cost and simple enough that it could be used anywhere,” said Barry Lutz, a UW associate professor of bioengineering, an investigator with the Brotman Baty Institute for Precision Medicine, and senior author of the paper. “We hope that the low cost will make high-performance testing more accessible locally and around the world.”

The Harmony test uses a “PCR-like” approach to detecting the virus — samples are obtained using a nasal swab and processed with ready-to-use reagents using a series of simple steps. The kit is meant to be used with a low-cost detector that can be operated using a smartphone, which provides the results. Each detector can handle up to four samples at a time.

The team explains that one of their main reasons for designing this test kit was the need for affordable and easy-to-use COVID-19 tests that provide reliable accuracy. Many at-home antigen kits available today test for pieces of the virus, not traces of its genetic material, and are only about 80-85% accurate and may be less accurate with the Omicron strain. PCR (polymerase chain reaction) tests are much better — providing around 95% accuracy — but are slow and cannot be carried out at home, as they require specialized devices and training to process. The Harmony kit is meant to combine the strengths of both of these types of tests.

Preliminary results show that Harmony is 97% accurate for nasal swabs. The test detects three different regions of the virus’ genome to help keep it effective against new strains: if a new variant of the virus develops many mutations in one region, the test can still detect the other two. The Harmony kit can detect the Omicron strain.

The step that makes PCR tests so time- and technology-intensive is a series of a few dozen heating and cooling cycles. Temperatures need to be very accurately controlled during these cycles to maintain the integrity of the sample. The Harmony test uses a similar method, known as RT-LAMP (reverse transcription loop-mediated isothermal amplification), with the key difference being that this doesn’t require the same temperature cycling.

“This test operates at a constant temperature, so it eliminates the time to heat and cool and gives results in about 30 minutes,” said Lutz.

Together with two of his colleagues, Lutz set up a new company for the UW — Anavasi Diagnostics — which will take the Harmony kit from an experimental device to a commercially-available product. The team believes that the kit will first be available for clinics and other medical institutions, then in settings where monitoring for infections is required, such as workplaces or schools. After these needs are met, they will adapt the test for home use.

“For a long time, the options have been either a PCR test that is expensive and typically takes a day or more to get a result, or a rapid antigen test that gives fast results and is low cost, but typically has lower accuracy than a lab PCR test,” said Lutz. “From the first day, we designed our test to be manufacturable at low cost and high volume, while delivering fast results with PCR-like performance.”

“We plan to make our test accessible and affordable throughout the world,” he adds.

The paper “Harmony COVID-19: A ready-to-use kit, low-cost detector, and smartphone app for point-of-care SARS-CoV-2 RNA detection” has been published in the journal Science Advances.