Low-cost smartphone based test can accurately detect COVID-19 in 20 minutes

Researchers in the US have developed a low-cost smartphone based diagnostic tool for COVID-19 that combines the speed of over-the-counter antigen tests with the accuracy of PCR tests.

The Harmony COVID-19 test developed by researchers at the University of Washington in the US detects genetic material from the SARS-CoV-2 virus, the researchers said.

While the conventional PCR tests can take several hours, the Harmony kit can provide results in less than 20 minutes for some samples and with similar accuracy, they said.

“We designed the test to be low-cost and simple enough that it could be used anywhere,” said Bary Lutz, an associate professor at the University of Washington.

“We hope that the low cost will make high-performance testing more accessible locally and around the world,” said Lutz, senior author of the research paper published in the journal Science Advances.

The test uses a “PCR-like” method to detect the presence of the SARS-CoV-2 RNA genome in a nasal swab sample with the aid of a small, low-cost detector.

A smartphone is used to operate the detector and read the results, the researchers said. The detector can handle up to four samples at a time and would fit into a standard car’s glove compartment, they said.

The accuracy of COVID-19 tests has been a pressing matter throughout the pandemic. Many at-home antigen kits for COVID-19, which detect pieces of the proteins the virus creates instead of its genetic material, are 80-85 accurate.

The researchers noted that the accuracy of antigen kits may drop with the Omicron variant, which harbours a relatively high number of mutations not found in other strains.

PCR tests are generally 95 per cent accurate or better but require expensive equipment and a long wait for results. Initial results show that the Harmony kit is 97 per cent accurate for nasal swabs, according to the researchers.

The Harmony kit detects three different regions of the virus’ genome. If a new variant has many mutations in one region, the new test can still detect the other two, they said.

It can, for example, detect the Omicron variant, which has dozens of mutations in the region of the genome that encodes the so-called spike protein, the researchers said.

Though tests based on PCR are highly accurate, a key limitation is that PCR tests require dozens of cycles of heating and cooling to detect genetic material in a sample.

The new test overcomes this issue by relying on a method known as RT-LAMP, which doesn’t have the same stringent temperature-cycling requirements.

“This test operates at a constant temperature, so it eliminates the time to heat and cool and gives results in about 20 minutes,” said Lutz. The team spun out a new company, Anavasi Diagnostics, to develop the Harmony prototype kit into a product and scale up manufacturing to help address the ongoing shortage of COVID-19 diagnostic tests.

Lutz and colleagues hope the kits could be initially made available for use in clinics, as well as other settings such as workplaces and schools. Later, the researchers said they would like to adapt the test for home use.