After nearly six months of scrutinizing the smorgasbord of COVID-19 tests available globally, an independent diagnostics evaluation group has come to some conclusions: The world greatly needs rapid, affordable tests, but the quality of such tests varies widely. By contrast, slow tests that are sent off to laboratories—the kind broadly used in the U.S. and Europe—are performing well.
That’s according to the Foundation for Innovative New Diagnostics, or FIND, headquartered in Geneva, Switzerland. “People in low- and middle-income countries often do not have access to laboratories,” says Jilian Sacks, FIND’s COVID-19 Evaluation Programme Lead. “So the ability to have rapid tests, especially outside the hospital and in decentralized settings, is most critical moving forward. But we are seeing that there is a lot of variability in the performance of rapid tests,” she says.
Sacks’s organization in February took on the ambitious task of evaluating the performance of hundreds of COVID-19 tests that have been flooding the global market ever since the pandemic hit. FIND told Spectrum earlier this year that it would subject these tests to a slew of coronavirus samples and make the results public on its website. This week, we checked in to see how it’s going.
The most reliable tests, FIND has found, are molecular tests performed in a laboratory. These diagnostics are the go-to COVID-19 testing method in the U.S. and Europe. They identify the disease by looking for the virus’s genetic code using a tool called polymerase chain reaction, or PCR.
FIND has evaluated 23 molecular tests so far. All but two had a sensitivity of at least 95%, meaning the tests accurately detected positive samples 95% of the time. “We're seeing that generally, the companies that we selected to evaluate have quite good performance with their assays,” so there are several good options from which ministries of health can choose, Sacks says.
But molecular tests are slow. PCR takes only a few hours to perform, but people are having to wait days to get results back due to the logistics of transporting samples to a centralized laboratory with PCR capability.
“Global demand has continued to soar, and though there may be many companies that should be able to meet that demand, it will require continued, unprecedented scale-up of their manufacturing and distribution,” Sacks says.
Rapid tests, on the other hand, provide results right away, on the spot, without having to send off a sample to a centralized lab. This allows people to make decisions immediately about whether or not to quarantine. And rapid tests are sometimes the only way to get tested in low-resource regions where access to centralized laboratories is scarce. But these tests are not as accurate as molecular tests.
FIND is evaluating 41 different rapid tests—5 that spot antigens and 36 that look for antibodies. Antigens are the parts of the virus that the immune system recognizes, and finding evidence of them means the virus is present. Antibodies are produced from healthy cells as part of the body’s immune response to a virus, and finding those means the virus is, or was, in the body, and that the immune system responded. Both types of tests can be performed on-the-spot because they are less complex and don’t require a lab.
FIND has released results for four of the rapid antibody tests it is evaluating. Only one of them—an antibody test made by BTNX—correctly identified positive cases over 90% of the time. The performance of some of the other tests is so low that they provide little value.
Rapid antibody tests should have a sensitivity of at least 90%, according to new draft guidelines from the World Health Organization (WHO) released in early August. Rapid antigen tests should have a sensitivity of at least 70% to diagnose infection, according to the agency.
In addition to its own program, FIND is aggregating the independent evaluations of other organizations from around the world and making it available online. These data are sorely needed. Global regulators, such as the FDA, which would normally require a lot more data from diagnostic companies before allowing a test to be used commercially, have largely stepped out of the way. This has boosted innovation and hastened the availability of tests. But it also allows inaccurate tests onto the market, and shifts the burden of oversight to whomever wants to take on the job.
That’s the hole that FIND is trying to fill. “We have indeed heard from various ministries of health, that as companies are approaching them to offer their tests, they are looking to our website to see if we've evaluated the test and whether they feel comfortable with the results,” Sacks says.
It’s good to know that someone out there is testing the tests.
Emily Waltz is a contributing editor at Spectrum covering the intersection of technology and the human body. Her favorite topics include electrical stimulation of the nervous system, wearable sensors, and tiny medical robots that dive deep into the human body. She has been writing for Spectrum since 2012, and for the Nature journals since 2005. Emily has a master's degree from Columbia University Graduate School of Journalism and an undergraduate degree from Vanderbilt University. She aims to say something true and useful in every story she writes. Contact her via @EmWaltz on Twitter or through her website.