The coronavirus may be a lot more prevalent than even the horrifying statistics we know indicate. The known global number of cases (including the dead and the healed) is fast approaching 4.5 million, but that could be the tip of the iceberg. One reason for the murk is that testing is complicated, expensive and, mainly, slow. Results can take from hours to days.
Now, Prof. Gabby Sarusi of Ben-Gurion University of the Negev, Be’er Sheva, has invented an almost instantaneous, affordable breath test for SARS-CoV-2 based on spectroscopy, which outputs the positive or negative result in less than 1 minute – and even as little as 20 seconds – the university announced Wednesday.
The device, which can test one’s breath – another breakthrough – or nasal or throat swabs for the coronavirus, is still undergoing validation, a process of another two to three months. Mass production can hopefully begin from September or October. Moreover, the device is automated: If we assume 20 seconds per test, one device can get through 4,500 tests a day, Sarusi says.
Discovery of an almost instant test for the coronavirus is apposite news on the day scientists demonstrated that airborne droplets produced through speech could be a potentially significant mode of COVID-19 transmission. We all know people who spit when talking; in fact, we all do that even if we think we don’t.
Meanwhile, mass testing in Israel at least has been hampered partly because there wasn’t enough testing power to handle all the swab samples taken before the virus in them became inert. How much human handling will Sarusi’s new device need?
“It probably will need human attention at the beginning, but it can be made fully automated in the future – like a vending machine,” Sarusi tells Haaretz. He adds that the university has already patented a fraud detection concept for the device: to make sure people don’t fake-breathe into the intake in order to be cleared for flying, for instance.
The test stations will cost about $400,000 apiece, Sarusi says. Each diagnostic test should cost between $40 to $50, he projects, putting the technology on the affordable end of the scale. Several countries promise to provide coronavirus testing for free, but even if they have the capacity. ultimately somebody’s paying – the taxpayer, the insurance company, and so on. That cost per test can range from about $60 to the sky.
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Sometimes, the testing process involves starting by testing for other conditions, significantly inflating the total bill – even though it bears adding that if you have the flu or a cold, that doesn’t mean you don’t have COVID-19 too. You can have multiple diseases together.
Trouncing the ‘golden standard’
Prof. Sarusi, the deputy head for research at the Ben-Gurion School of Electrical and Computer Engineering, developed the chip on which the testing device is based within the framework of BGU’s Coronavirus Task Force, which was initiated by BGU President Prof. Daniel Chamovitz.
Sarusi’s device achieved 90 percent accuracy based on a sample of 120 Israelis, of whom 45 percent were infected and 55 percent were healthy, the professor says. Its rate of false positives and false negatives were 5 percent each.
No current tests are 100 percent accurate – neither swab tests from nose and throat based on polymerase chain reaction (PCR) technology; nor tests for coronavirus antibody in the blood.
Both the swab test and antibody test may produce a significant rate of false negatives, meaning the subject has COVID-19 but the test doesn’t show it. “PCR is the golden standard, but it has 70 to 80 percent accuracy that is very much dependent on the way the swab is taken,” Sarusi says. The only reason medicine takes swab results as reliable is the absence of any other benchmark, he explains.
Why are swab tests so unreliable? There could be a host of reasons beyond faultiness of the swab test itself. If the swab lies around for days before being actually tested, the virus “dies” and the test won’t work. If the swab test is administered too “early” in the disease process (typically, if one is exposed but isn’t symptomatic yet), if might produce a negative. Or, if the test is administered after recovery has begun, the swab could produce a negative result, but a test of the patient’s stool could still be positive.
As for the antibody test, if one is infected with the coronavirus, one typically develops antibodies that fight the virus in one’s body – but it takes a couple of weeks after infection to develop detectable levels of antibody. Within that time, patients reach peak infectiousness.
Nor do we know yet whether the antibody response is maintained over time. COVID-19 is caused by a species of coronavirus and, for what it’s worth, the common cold is caused by another species of coronavirus and our antibodies to that beastie disappear within a year. Which explains why you can get cold after cold after cold and never develop immunity to it. However, on the bright side, scientists say that antibodies to SARS, another cousin of the new virus, may last for three years.
How the test works: The coronavirus resonates
The clinical trials of the diagnostic device are being done in conjunction with the Defense Ministry; the ongoing trials will seek to determine if the test can identify the specific stage of COVID-19 infection as well as its presence, the university says.
How does the breakthrough breath test for coronavirus work, anyway? “Particles from a simple breath test or throat and nose swabs – such as are already currently used for other tests – are placed on a chip, with a dense array of metamaterial sensors, which was designed specifically for this purpose,” Sarusi explains.
“Metamaterial sensors” are nano-size antenna array on the electronic chip he invented, which is inside the Breathalyzer, he says.
The system analyzes the biological sample and outputs a positive/negative result into a system connected to the cloud, which means the result can be shared with the authorities, making it easier to track viral spread.
Technically, it turns out that the coronavirus resonates in the terahertz spectral range, so it could theoretically be detected through terahertz spectroscopy.
“We asked ourselves, since this virus is just like a nano-particle or a quantum dot with a diameter between 100nm to 140nm in terms of its size and electrical properties, can we detect it using methods from the worlds of physics, photonics and electrical engineering?” Sarusi says. “We discovered that the answer is yes, this virus resonates in the terahertz frequency, and spectroscopy in these frequencies reveals it promptly.” Now you know.
Asked if the virus has to be “fresh” to resonate, Sarusi says they have been testing the device on people providing samples on the spot, so they don’t know what would happen with “older” samples at this point. What’s for sure is the devices will be made in Israel, either by a company subcontracted to make them, or a new company set up for that purpose, he says.
Meanwhile, the news that infected people spread coronavirus when they speak, published in PNAS on Wednesday, is hardly shocking.
Speaking produces thousands of oral fluid droplets per second, report Philip Anfinrud, Adriaan Bax and colleagues, who used lasers to examine the small-sized droplets – which may linger in the air for up to eight minutes after you emit them.
If there’s good news, it’s that the droplets you spew while you speak slowly evaporate – really. But the bad news is that their calculations show that 1 minute of loud speaking could generate more than 1,000 virus-containing droplets that would remain airborne for 8 minutes or longer.
So, wear masks everywhere, including at the office and absolutely on public transportation, folks. Normal speaking confers a real risk and a lot of people are infected with the coronavirus and don’t even know it yet – but can be spreading it everywhere just by saying hello.