Develop portable test to detect COVID-19 fast, cheap and accurate

Scientists in the United States have developed a portable device that reliably detects COVID-19 from a saliva sample in less than 30 minutes, according to a study published in Nature.

This new instrument, of which many components can be manufactured with a 3D printer, performs coronavirus tests capable of detecting a single virus particle for each 1-microliter drop of liquid, the researchers highlight in a statement.

“We have developed a fast, highly sensitive and accurate test, and a portable device that works with a COVID-19 test battery that can be used anywhere and at any time,” explains Huimin Zhao, lead author of this work.

Although it is still a prototype, they estimate that its cost could be below 78 dollars (about 65 euros), while the price of the reagents and other elements necessary to carry out the tests would be around 6 or 7 dollars (less than 6 euros) for each test.

The researchers recall that the existing technology to detect the coronavirus is complex, expensive, slow and cumbersome, so it must be in the hands of expert analysts.

Its development has been made possible by recent advances by Zhao’s team, who discovered a system for producing artificial restriction enzymes that can be programmed to recognize and cleave specific genes in an organism’s genome.

Once inserted into the device, the DNA guides that carry these enzymes mark the viral genes of interest with a dye that emits a fluorescence after being excised, indicating that it is a positive test.

With this new technology, called Portable and Scalable Testing (SPOT), it is not necessary to resort to the complex cooling and heating process that each sample undergoes in many of the tests available today.

Additionally, SPOT can detect multiple genes in each sample, increasing its reliability over single-gene tests, which can yield inaccurate or inconclusive results.

Another advantage, the authors note, is that it only requires saliva and eliminates the need to obtain samples through nasal swabs.

In their trials, the team of experts evaluated the effectiveness of SPOT by analyzing 104 saliva samples. Thus, they found that it accurately identified 28 out of 30 positive samples for SARS-CoV-2, the coronavirus that causes COVID, and 73 out of 74 negative samples.

“Based on the available data, the precision of our test is comparable to or better than other SARS-CoV-2 tests,” says Zhao.

In addition, the researchers tested SPOT with samples that did or did not contain the influenza virus, the new coronavirus, and three other human coronaviruses, and showed that it identifies SARS-CoV-2, whether or not other viruses were present.