New Technology Combines Speed of Rapid Antigen Test with Accuracy of PCR Testing to Detect COVID-19 in 4 Minutes

The test developed by researchers at Fudan University (Shanghai, China) uses a hypersensitive electromechanical biosensor to detect nucleic acids that were earlier difficult to identify owing to their low concentration in test samples. The sensor which uses microelectronics to analyze genetic material from swabs could reduce the need for time-consuming lab tests for diagnosing COVID-19.

PCR tests are the most accurate and sensitive for detecting SARS-COV-2, the virus that causes COVID-19, although they can take several hours to deliver results. Rapid antigen tests are a quicker alternative and deliver results in 15 minutes but are less reliable than PCR tests which are more accurate due to their greater sensitivity. In comparison to PCR tests, antigen tests require a higher concentration of the virus to exhibit a positive result due to which they are more likely to show a false negative. Antigen tests look for pieces of virus-infected proteins, while PCR tests search for viral genetic material such as nucleic acids and RNA.

Currently, there is no technology that can properly detect COVID-infected nucleic acids and RNA without using extraction and amplification methods which require a lab environment. The new method that uses a hypersensitive electromechanical biosensor to detect nucleic acids offers speed, ease of operation, high sensitivity and portability. Portable tests based on this technology could be used for on-site COVID-19 testing at airports, clinics, emergency departments and at home, as well as for quickly diagnosing other types of diseases.

In a clinical trial of the new test, the researchers collected nasal samples from 33 PCR-positive COVID-19 patients, 23 PCR-negative patients, six influenza-positive patients and 25 healthy volunteers. The researchers found that the test accurately processed all the cases without any errors in less than four minutes. The trial was conducted on a small sample, and if the 100% accuracy rate was replicated in a larger test sample, then the new test could be a game changer in COVID-19 diagnosis.

"We implemented an electromechanical biosensor for the detection of SARS-CoV-2 into an integrated and portable prototype device, and show that it detected (virus RNA) in less than four minutes," the team said in a peer-reviewed article describing their molecular electromechanical system, or MolEMS, in the journal Nature Biomedical Engineering.

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