A Breath of Fresh Air for COVID-19 Testing

You’ve undoubtedly heard a lot about COVID-19 testing lately. Perhaps you’ve even undergone a diagnostic test to check on a cold, or were curious to see if you developed antibodies without knowing you’d been infected. There are two different types of tests used for COVID-19 and viruses in general—diagnostic, which shows active infection, and antibody, which looks for antibodies made by the immune system in response to a specific virus.

Diagnostic tests fall into two categories: molecular and antigen. Also known as a nucleic acid amplification test, RT-PCR test, or LAMP test, these are collected via nasal or throat swab, or saliva in a few cases. They generally return results within a week and are typically highly accurate in diagnosing viral infection. Antigen tests, also known as rapid diagnostic tests, also collect samples from nasal or throat swabs, but return results in an hour or less. However, while positive results are highly accurate, negative results might need confirmation from a molecular test. Antibody tests, also known as serology tests, show past COVID-19 infection through a fingerstick or blood draw, and return results within three days.

There are also novel methods gaining traction. Rapid, point-of-care diagnostic tests (both molecular and antigen) collect mucus from the nose or throat to analyze in the doctor’s office, returning results within minutes. With a doctor’s prescription, at-home collection tests can be sent directly from the patient to the lab. And saliva tests let patients spit into a tube rather than endure an uncomfortable nose or throat swab.

One of the latest and most promising COVID-19 testing innovations has recently emerged from researchers at Israel’s Technion-Israel Institute of Technology—a rapid, inexpensive coronavirus breath test. The researchers reported results of a clinical trial of 140 people from Wuhan, China, in ACS Nano in mid-August that confirmed correct identification of all positive patients.

The device resembles a breathalyzer, using gold nanoparticles linked to molecules that are sensitive to volatile organic compounds present in COVID-19 patients’ exhaled breath. According to Wolfson Faculty of Chemical Engineering at the Technion professor Hossam Haick, the test is fully automatic and there’s no need for anyone to contact the patient to handle their sample.

“You just blow into the device, which is the size of a smartphone, for two to three seconds, from a distance of 2 centimeters away,” he told The Times of Israel. “There are no accessories, it requires no lab processing, and it gives results within 30 seconds of blowing.”

The test, developed together with Dr. Yoav Broza of the Technion’s Russell Berrie Nanotechnology Institute and Wuhan researchers, is based on a device professor Haick invented a few years ago to detect cancer. The cancer test isn’t yet in use because it’s still undergoing regulatory assessment. However, Haick expects the COVID-19 version to be swiftly accredited because of the urgency around coronavirus testing.

“If everything goes well with further clinical studies, I hope it will be available and regulated within six months,” he said.

Current prototypes for the “breathalyzer” are half-held, but Haick said the final product will require no touch at all, making the risk of cross-contamination very low. Nanose Medical, where Haick serves as chief technology officer, is developing the technology for the market. Haick predicted tests will cost about $2 to $3 dollars per person. The test was remarkably accurate in the trial—of the 140 people tested, 49 of them were confirmed coronavirus patients. The breathalyzer identified all carriers as COVID-positive, but erred with the results of seven healthy people and reported them positive as well.

Regular swab tests also return false positives, but it’s not exactly known how many because people assume the result is correct and they are asymptomatic. Doctors aren’t as concerned with false positives because the most they risk is the inconvenience of needlessly worrying and quarantining people. False negatives, however, can prompt people to wrongly assume they’re virus-free and spread the infection further.

Haick told The Times of Israel that in his design he emphasized accurate assessment of patients afflicted with respiratory conditions other than coronavirus. “Think about winter time, when people will have lots of conditions, such as influenza and colds, that make them feel sick but aren’t COVID-19, and it’s very important we can differentiate between them correctly,” he commented.

There have been a great deal of reports about new quick-testing technologies—Abbott’s rapid ID NOW COVID-19 test in particular raised some controversy over false negatives. But Haick said his test has the credentials to prove its worth. The trial was approved by Chinese authorities, and unlike some other innovations, was peer-reviewed and published in a scientific journal to meet the scientific community’s standards.

In the test set, the device showed 76 percent accuracy in distinguishing COVID-19 cases from controls and 95 percent accuracy in discriminating COVID-19 cases from lung infections. The sensor could also distinguish, with 88 percent accuracy, between sick and recovered COVID-19 patients. Although the test needs to be validated in more patients, the researchers said it could be useful for screening large populations to determine which individuals need further testing.