Chinese researchers develop 4-minute PCR test

Chinese scientists say they have developed a COVID-19 test that can process results as accurately as PCR tests in less than four minutes.

PCR tests are the most accurate on the market, but must be processed in a lab, which so far takes a few hours at minimum. When labs are overwhelmed by local surges in infection, processing can last days.

Quicker, 15-minute rapid antigen tests are less reliable than the PCR alternative.

Researchers at Fudan University collected nasal samples from 33 PCR-positive COVID-19 patients, 23 PCR-negative patients, six influenza-positive patients and 25 healthy volunteers. The test accurately processed all cases without error in under four minutes, according to a peer-reviewed study published Mondayin the journal Nature Biomedical Engineering.

PCR tests are more precise than antigen tests because they are more sensitive. Antigen tests require a higher concentration of the virus than PCR tests to show a positive result. This means antigen tests are more likely to show a false negative.

Antigen tests seek pieces of virus-infected proteins, while PCR tests search for viral genetic material like nucleic acids and RNA.

Until now, no technology has been created to properly detect COVID-infected nucleic acids and RNA without using extraction and amplification methods, for which you need a lab environment.

The Fudan University research was conducted on a small sample, said Andrew Ching, a professor of economics jointly appointed to the Johns Hopkins Department of Economics and the Bloomberg School of Public Health.

If the 100% accuracy rate were to hold up in a larger test sample, Ching said, "it could be a game changer."

However, he said, if the accuracy rate doesn't hold up at a larger scale and becomes similar to that of the antigen test, it won't make a difference. 

May allow on-site testing at airports, clinics, at home

Ching said that because the structure of China's government places more authority toward the top, if the test is able to be produced at a large scale, he wouldn't be surprised to see manufacturers coming out with versions by the summer. 

"China tends to be more open to experimental methods," he said, allowing approval processes to move more quickly than they would in Europe or the US.

The test developed at Fudan University uses a hypersensitive electromechanical biosensor to detect nucleic acids previously difficult to identify due to their low concentration in test samples.

Researchers said the development of portable tests featuring such technology could enable on-site testing at airports, clinics, emergency departments and at home. They added it could also be used for the quick diagnosis of other types of diseases.

There are countless brands of COVID-19 rapid at-home tests currently on the market, which vary in accuracy.

Edited by: Carla Bleiker

This article has been updated to include statements by Andrew Ching, a professor of economics jointly appointed to the Johns Hopkins Department of Economics and the Bloomberg School of Public Health.