Group’s report also suggests that at-home clinical laboratory tests for COVID-19 that are difficult to use may lead to inaccurate results
At-home clinical laboratory tests for COVID-19 have become quite popular. But how accurate are they? Now, an independent safety organization has investigated COVID-19 rapid antigen tests to find out how easy—or not—they are to use and what that means for the accuracy of the tests’ results.
ECRI (Emergency Care Research Institute) of Plymouth Meeting, Penn., “conducted a usability evaluation to determine if there were any differences in ease of use for the rapid COVID-19 tests,” according to the company’s website.The nonprofit was founded in the 1960s by surgeon and inventor Joel J. Nobel to evaluate medical devices that have been approved by the U.S. Food and Drug Administration (FDA).
“Because of the urgency in providing useful information to consumers as quickly as possible, ECRI selected the seven test kits based on retail availability,” ECRI noted.
ECRI ranked the seven over-the-counter (OTC) at-home rapid antigen tests according to their SUS usability ratings. The System Usability Scale (SUS), invented by John Brooke in 1986, “rates products on a scale of 0 to 100 with 100 being the easiest to use. More than 30 points separated the top and bottom tests analyzed,” according to Managed Healthcare Executive.
Of the seven rapid antigen test kits for COVID-19, ECRI found “noteworthy usability concerns” and “significant differences in ease of use.” None of the tests achieved a SUS rating of “excellent,” ECRI stated in a press release.
“Our evaluation shows that some rapid [COVID-19] tests are much easier to use than others. If given options, consumers should choose tests that are the easiest to use because when a [COVID-19] test is difficult for a consumer to use, it may lead to an inaccurate result,” said ECRI President and CEO Marcus Schabacker, MD, PhD, in a news release. Marcus “is a board-certified anesthesiologist and intensive care specialist with more than 35 years of healthcare experience in complex global environments, and more than 20 years of senior leadership responsibilities serving the medical device and pharmaceutical industries across the healthcare value chain,” states ECRI. (Photo copyright: Biz Journals.)
Seven Rapid Antigen Tests for SARS-CoV-2 Evaluated
As clinical laboratory scientists and pathologists know, it’s possible for different test methodologies for the same biomarker to produce dissimilar results. Another factor affecting medical laboratory test accuracy is the variability from one manufacturing batch or lot to another. And, as the ECRI report suggests, how a specimen is collected and handled can affect accuracy, reliability, and reproducibility of the test results generated by that specimen.
These are the OTC COVID-19 rapid antigen tests ECRI evaluated and their SUS ratings:
Some tests, the ECRI analysts found, required “fine motor control” or were packed with written instructions ECRI determined were too small for older adults to read.
How ECRI Evaluated the COVID-19 Rapid Antigen Tests
SUS reviewers took each rapid test and completed questionnaires specifying their level of agreement (on a range of one to five) with these statements. (Edited by Dark Daily for space):
Desire to use
Perception of unnecessary complexity
Easy to use
Support of a technical person needed
Functions well-integrated
Too much system inconsistency
Easy to learn for most people
A very cumbersome system to use
Feeling of confidence in use
A need to learn before getting going
ECRI then used an algorithm to derive an aggregate score (from 0 to 100) for each test, the report noted.
“Based on the aggregate SUS scores, none of the COVID-19 test kits would be judged to have ‘excellent’ usability. The On/Go, CareStart, Flowflex test kits we rate as ‘very good’ as the usability score for these kits falls just short of ‘excellent,’” the report said.
Some of the positive responses ECRI received from the SUS participants included:
“One of the simpler tests to use with good, printed instructions,” (On/Go and CareStart).
“Cassette makes handling without touching test strip easy,” (CareStart and Flowflex).
“The QR (quick-response) code-linked instructional video is helpful, but probably not needed,” (QuickVue).
“Once the swab is inserted into the test card, the test seems less likely to be spilled or disturbed than other test kits,” (BinaxNOW).
Is it Time for Rapid COVID-19 Antigen Tests?
Unlike RT-PCR tests that can take hours or days to return results, rapid antigen tests provide a quick result that’s used for screening worldwide. And with the COVID-19 Omicron variant spreading rapidly around the world, speed is much needed, according to Stephen Kissler, PhD, Research Fellow in the department of immunology and infectious diseases at Harvard’s T.H. Chan School of Public Health.
“I think the rapid tests provide some of the best protection we have against the spread of disease, especially as we now have a variant on hand that’s going to be able to cause an awful lot of breakthrough infections,” Kissler told The Atlantic-Journal Constitution.
One way clinical laboratory leaders can help is to reach out in their local markets and provide information on the importance of appropriate sampling and collection for accurate results from rapid COVID-19 antigen testing.
The antibodies target portions of the SARS-CoV-2 spike protein that resist mutation, potentially leading to better treatments and vaccines
One challenge in the battle against COVID-19 is the emergence of SARS-CoV-2 variants, especially the Delta variant, which may be more resistant to neutralizing antibodies compared with the original coronavirus. But now, scientists led by researchers at the Fred Hutchinson Cancer Research Center (Fred Hutch) in Seattle say they have identified antibodies that could be broadly protective against multiple sarbecoviruses, the subgenus that contains SARS-CoV-2 as well as SARS-CoV-1, the virus responsible for the 2002-2004 severe acute respiratory syndrome (SARS) outbreak.
In “SARS-CoV-2 RBD Antibodies That Maximize Breadth and Resistance to Escape,” the researchers described how they compared 12 antibodies obtained from patients infected with either SARS-CoV-2 or SARS-CoV-1. They pointed to one antibody in particular—S2H97—that could lead to development of new vaccines and therapies against current and future variants. It might even protect against sarbecoviruses that have not yet been identified, they wrote.
Unsaid in the news release about these research findings is the fact that these particular antibodies could eventually become useful biomarkers for clinical laboratory tests designed to help physicians determine which patients have these antibodies—and the protection from infection they represent—and which do not.
So far, however, S2H97 has only been tested in hamsters. But results are promising.
“This antibody, which binds to a previously unknown site on the coronavirus spike protein, appears to neutralize all known sarbecoviruses—the genus of coronaviruses that cause respiratory infections in mammals,” said Jay Nix, PhD, an affiliate in Berkeley Lab’s Biosciences Area and Beamline Director of the Molecular Biology Consortium at Berkeley Lab’s Advanced Light Source (ALS), in a Berkeley Lab news release. “And, due to the unique binding site on mutation-resistant part of the virus, it may well be more difficult for a new strain to escape,” he added.
Scientists have long known that the SARS-CoV-2 virus uses the spike protein to attach to human cells. The federal Centers for Disease Control and Prevention (CDC) notes that the variants have mutations in their spike proteins that make some of them more transmissible.
The Delta variant, the CDC notes, was the predominant variant in the US as of August 28, 2021. It “has been shown to have increased transmissibility, potential reduction in neutralization by some monoclonal antibody treatments, and reduction in neutralization by post-vaccination sera,” the agency states.
The key to S2H97, the researchers wrote, is that it targets a portion of the spike protein that is common among sarbecoviruses, and that is likely to be resistant to mutations.
The researchers used a variety of techniques to analyze how the 12 antibodies bind to the virus. They “compiled a list of thousands of mutations in the binding domains of multiple SARS-CoV-2 variants,” Nature reported. “They also catalogued mutations in the binding domain on dozens of SARS-CoV-2-like coronaviruses that belong to a group called the sarbecoviruses. Finally, they assessed how all these mutations affect the 12 antibodies’ ability to stick to the binding domain.”
William Schaffner, MD (above), Professor of Preventive Medicine in the Department of Health Policy as well as Professor of Medicine in the Division of Infectious Diseases at the Vanderbilt University School of Medicine in Nashville, believes that “people who test positive for SARS-CoV-2 and who are at risk of progressing to severe disease—including those who are over the age of 65 years and those who have weakened immune systems—should talk with a doctor about receiving monoclonal antibody treatment,” Medical News Today reported. “[The monoclonal antibody treatment is] designed to prevent the evolution of the infection from a mild infection into a serious one,” he noted. “In other words, you’ve just [contracted the virus], but we can now give you a medication that will help prevent [you] being hospitalized and getting seriously ill.” (Photo copyright: Vanderbilt University.)
Earlier Antibody Treatment Receives an EUA from the FDA
In issuing the EUA for sotrovimab, the FDA cited “an interim analysis from a phase 1/2/3 randomized, double-blind, placebo-controlled clinical trial in 583 non-hospitalized adults with mild-to-moderate COVID-19 symptoms and a positive SARS-CoV-2 test result. Of these patients, 291 received sotrovimab and 292 received a placebo within five days of onset of COVID-19 symptoms.”
Among these patients, 21 in the placebo group were hospitalized or died compared with three who received the therapy, an 85% reduction.
“While preventive measures, including vaccines, can reduce the total number of cases, sotrovimab is an important treatment option for those who become ill with COVID-19 and are at high risk—allowing them to avoid hospitalization or worse,” stated Adrienne E. Shapiro, MD, PhD, of the Fred Hutchinson Cancer Research Center in a GSK news release. Shapiro was an investigator in the clinical trial.
The EUA allows use of sotrovimab in patients who have tested positive for SARS-CoV-2, have mild-to-moderate symptoms, and “who are at high risk for progression to severe COVID-19, including hospitalization or death. This includes, for example, individuals who are 65 years of age and older or individuals who have certain medical conditions.” It is not authorized for patients who are hospitalized or for those who require oxygen therapy.
The therapy was originally known as VIR-7831. The companies say they have developed a similar treatment, VIR-7832, with modifications designed to enhance T cell function against the disease.
The antibody, they wrote, targets a region of the SARS-CoV-1 spike protein that is “highly conserved” among sarbecoviruses. Clinical laboratory testing, they wrote, also indicated that the therapy was likely to be effective against known SARS-CoV-2 variants.
“Our distinctive scientific approach has led to a single monoclonal antibody that, based on an interim analysis, resulted in an 85% reduction in all-cause hospitalizations or death, and has demonstrated, in vitro, that it retains activity against all known variants of concern, including the emerging variant from India,” stated Vir Biotechnology CEO George Scangos, PhD, in the GSK news release. “I believe that sotrovimab is a critical new treatment option in the fight against the current pandemic and potentially for future coronavirus outbreaks, as well.”
Pathologists and clinical laboratory managers working with rapid molecular tests and antibody tests for COVID-19 will want to monitor the development of monoclonal antibody treatments, as well as further research studies that focus on these specific antibodies.
Developers of medical laboratory tests had high hopes that cheap saliva-based tests would compete with at-home OTC tests that use nasal swabs, but skepticism among scientists continues
Reverse-transcription polymerase chain reaction (RT-PCR) technology has become the standard for clinical laboratory diagnostic testing used to detect the presence of the SARS-CoV-2 coronavirus. However, to enable more widespread testing, some public health experts have called for deployment of cheap, rapid, saliva-based antigen tests that could be self-administered by consumers in their homes.
Despite the technology’s lower sensitivity compared with RT-PCR testing, the idea of “fast-and-frequent” universal antigen testing has gained support as a possible game-changer against the outbreak, the New York Times reported.
The FDA recently took a step in this direction with its first emergency use authorization for the Ellume COVID-19 at-home antigen test. But other developments suggest that these tests may fall short of the lofty vision initially outlined by the experts.
Ellume’s COVID-19 Home Test (above) received emergency use authorization from the FDA on December 15. In a press release, Ellume claimed its rapid-antigen test, “demonstrated a sensitivity of 96% and specificity of 100%, and in asymptomatic individuals, the test demonstrated a sensitivity of 91% and specificity of 96%. This level of accuracy across both symptomatic and asymptomatic individuals is crucial in mitigating the spread of an infectious disease like COVID-19.” (Photo copyright: Ellume.)
The Promise of Rapid Antigen COVID-19 Tests
In a column he wrote for Time in July, Ashish K. Jha, MD, MPH, a practicing General Internist and Dean of the Brown University School of Public Health, described the promise of rapid antigen tests. “Imagine spitting on a special strip of paper every morning and being told two minutes later whether you were positive for COVID-19,” he wrote. “If everyone in the United States did this daily, we would dramatically drop our transmission rates and bring the pandemic under control.”
Another advocate for this approach is Michael Mina, MD, PhD, an assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health and a core member of the School’s Center for Communicable Disease Dynamics (CCDD). In a commentary for Time in November he wrote, “Widespread and frequent rapid antigen testing (public health screening to suppress outbreaks) is the best possible tool we have at our disposal today—and we are not using it.”
However, one major issue with antigen testing is sensitivity. “Antigen tests require higher levels of virus than qPCR [quantitative polymerase chain reaction] to return a positive result,” Jha wrote in Time. However, he contends, “the frequency of testing and the speed of results” counter concerns about accuracy.
Even with lower sensitivity, Jha wrote, the quicker test results from antigen tests “would identify viral loads during the most infectious period, meaning those cases we care most about identifying—at the peak period of infectiousness—are less likely to be missed.”
As the FDA explains, RT-PCR molecular tests “detect the virus’ genetic material,” whereas, according to an article published in Nature, titled, “Fast Coronavirus Tests: What They Can and Can’t Do,” antigen tests can “detect specific proteins … on the surface of the virus, and can identify people who are at the peak of infection, when virus levels in the body are likely to be high.”
At-Home Antigen Tests Receive EUAs
The new antigen test developed by Ellume is “the first over-the-counter (OTC) fully at-home diagnostic test for COVID-19,” the FDA said in a press release. The user self-administers a nasal swab and places it in an analyzer connected to a smartphone app. It can deliver results in 20 minutes. The company states that its test has overall sensitivity of 95% and specificity of 97% based on a clinical study of 198 subjects in a simulated home setting.
Jeffrey Shuren, MD, JD, Director of FDA’s Center for Devices and Radiological Health, said in the FDA press release, “This test, like other antigen tests, is less sensitive and less specific than typical molecular tests run in a lab. However, the fact that it can be used completely at home and return results quickly means that it can play an important role in response to the pandemic.”
Ellume expects to deliver about 20 million tests to the US by the end of June 2021. Multiple outlets reported that the test will cost about $30, AP News reported.
Meanwhile, the FDA also authorized at-home use of Abbott’s BinaxNOW rapid antigen test, which was previously authorized for use in point-of-care settings. This test, which requires a prescription, will sell for $25.
In a series of tweets, Harvard’s Mina applauded both moves, but he wrote that they [antigen tests] still fall short of his vision for fast and frequent testing. He described Abbott’s BinaxNOW as “the type of rapid test I have been calling for,” but said he’d like to see tests priced far less and available without a prescription.
Diminishing Prospects for Saliva-based Antigen Tests?
All rapid antigen tests authorized by the FDA so far require nasopharyngeal and/or nasal swab specimens, and it appears that it may be a long time, if ever, before saliva-based antigen tests are available. The New York Times (NYT) reported in October that two companies working on antigen tests—E25Bio and OraSure (NASDAQ:OSUR)—have dropped plans to enable use of saliva.
“If I was placing a bet—which I am, because I’m leading an antigen-based testing company—I would say it’s going to be very difficult for antigen-based testing to work on saliva samples,” E25Bio founder Bobby Brooke Herrera, PhD (above with E25Bio co-founder and Chief Technology Officer Irene Bosch) told the NYT. (Photo copyright: WCVB-TV.)
One advantage of a saliva-based test is that it would be easier to self-administer. “But as they continued to tinker with their tests, researchers at both E25Bio and OraSure found saliva’s performance to be more lackluster than anticipated, and were forced to pivot,” the New York Times reported. Instead, both companies will seek authorization for use of their tests with nasal swabs.
HHS Contract for Antigen Tests Brings High Rates of False Positives
A recent investigative story in ProPublica, titled, “Rapid Testing Is Less Accurate than the Government Wants to Admit,” raised additional questions about rapid antigen testing. In August, the US Department of Health and Human Services announced it had awarded a $760 million contract for 150 million Abbott BinaxNOW tests to be distributed to schools and nursing homes. But later, according to ProPublica, healthcare workers in Nevada and Vermont reported high rates of false positives.
“With the benefit of hindsight, experts said the Trump administration should have released antigen tests primarily to communities with outbreaks instead of expecting them to work just as well in large groups of asymptomatic people,” ProPublica reported. “Understanding they can produce false results; the government could have ensured that clinics had enough for repeat testing to reduce false negatives and access to more precise PCR tests to weed out false positives.”
A few weeks after the reports from Nevada and Vermont, the FDA issued a letter advising clinical laboratories and healthcare providers about the possibility of false positives, along with steps they could take to improve accuracy.
Though some experts remain hopeful about “fast-and-frequent” testing, others are skeptical and say more research is needed to assess the value of this approach. “We are open to thinking outside the box and coming up with new ways to handle this pandemic,” Esther Babady PhD, D(ABMM) of Memorial Sloan Kettering Cancer Center, told the New York Times. However, she added, “the data for that is what’s missing.”
Nevertheless, were at-home rapid saliva-based antigen tests to become a common choice for healthcare consumers, clinical laboratories that perform RT-PCR testing for COVID-19 could see a marked decrease in orders. Thus, regardless of the current state of antigen testing, its development is worth watching.
Abbott sends the SARS-CoV-2 test results directly to patients’ smartphones, which can be displayed to gain entrance into areas requiring proof of COVID-19 testing
There is no greater example that COVID-19 is a major force for change in the clinical laboratory industry than the fact that—though the US federal government pays 50% of the nation’s total annual healthcare spend of $3.5 trillion—it recently spent $760 million to purchase 150 million COVID-19 tests from Abbott Laboratories (NYSE:ABT), an American multinational medical devices and healthcare company headquartered in Abbott Park, Ill., “to expand strategic, evidence-based testing in the United States,” according to the company’s website.
In August, the federal Food and Drug Administration (FDA) granted an emergency use authorization (EUA) to Abbott for its BinaxNOW portable rapid-response COVID-19 antigen (Ag) test. The credit-card sized test costs $5 and can return clinical laboratory test results in minutes, rather than hours, days, or in some cases, weeks, the Wall Street Journal (WSJ) reported.
The test includes a free smartphone app called NAVICA, which enables those tested to receive their test results directly on their mobile devices—bypassing the patient’s primary care physicians.
According to Abbott’s website, the app “allows people who test negative to get an encrypted temporary digital NAVICA Pass, similar to an airline boarding pass. NAVICA-enabled organizations will be able to verify an individual’s negative COVID-19 test results by scanning the individual’s digital NAVICA Pass to facilitate entry into facilities.”
This feature of Abbott’s new COVID-19 test is a good example of how quickly innovation in the medical laboratory testing profession is bringing new features and new capabilities to the marketplace. By marrying the SARS-CoV-2 test with the NAVICA Pass feature, Abbott hopes to deliver increased value—not just to physicians and their patients—but also to employers with employee screening programs and federal government programs designed to screen federal employees, as well as being used for screening travelers at airports and other transportation hubs.
Abbott appears to be banking that in the future such identification will be required to “enter organizations and other places where people gather,” as the company’s website states.
Testing Limited to CLIA-Certified Clinical Laboratories
An HHS news release announcing the government’s planned distribution of the BinaxNOW tests stated that “Testing will be potentially deployed to schools and to assist with serving other special needs populations.”
In the news release, Alex Azar, HHS Secretary, said, “By strategically distributing 150 million of these tests to where they’re needed most, we can track the virus like never before and protect millions of Americans at risk in especially vulnerable situations.”
The EUA adds that “Testing of nasal swab specimens using [BinaxNOW] … is limited to laboratories certified under CLIA that meet the requirements to perform high, moderate, or waived complexity tests. This test is authorized for use at the [point of care], i.e., in patient care settings operating under a CLIA Certificate of Waiver, Certificate of Compliance, or Certificate of Accreditation.”
The FDA’s EUA describes the BinaxNOW portable rapid-response COVID-19 antigen test (above) as “a lateral flow immunoassay intended for the qualitative detection of nucleocapsid protein antigen from SARS-CoV-2 in direct nasal swabs from individuals suspected of COVID-19 by their healthcare provider within the first seven days of symptom onset.” The test costs $5 and Abbott sends results directly to the patient’s smartphone using the free NAVICA app included with the test. (Photo copyright: Abbott Laboratories.)
IVD Companies See Boom in COVID-19 Test Sales
Demand for COVID-19 testing has created opportunities for in vitro diagnostics (IVD) companies that can develop and bring tests to market quickly.
Recent issues of Dark Daily’s sister print publication—The Dark Report (TDR)—covered IVD companies’ second quarter (Q2) boom in sales of COVID-19 instruments and tests, while also noting a fall-off in routine clinical laboratory testing during the COVID-19 pandemic.
Abbott Laboratories saw molecular diagnostics sales increase 241% in Q2 driven by $283 million in sales of COVID-19 testing, while rapid diagnostic COVID-19 testing rose 11% on $180 million in sales in Q2, TDR reported, based on Abbott data.
“There is huge economic incentive for diagnostic companies to develop technologies that can be used to create rapid tests that are cheap to perform,” said Robert Michel, Publisher and Editor-in-Chief of TDR and Dark Daily. “In this sense, COVID is a major force for change.”
“This new COVID-19 antigen test is an important addition to available tests because the results can be read in minutes, right off the testing card,” said Jeff Shuren, MD, JD (above), Director of the FDA’s Center for Devices and Radiological Health (CDRH), in an FDA news release announcing the federal government’s $760 million purchase of 150 million Abbott BinaxNOW rapid-response antigen COVID-19 tests. “This means people will know if they have the virus in almost real-time. Due to its simpler design and the large number of tests the company anticipates making in the coming months, this new antigen test is an important advancement in our fight against the pandemic.” (Photo copyright: The New York Times.)
Thus, Abbott is determined to ensure this product launch is successful and that the test works as promised. According to a news release, “In data submitted to the FDA from a clinical study conducted by Abbott with several leading US research universities, the BinaxNOW COVID-19 Ag Card demonstrated sensitivity of 97.1% (positive percent agreement) and specificity of 98.5% (negative percent agreement) in patients suspected of COVID-19 by their healthcare provider within the first seven days of symptom onset.”
“The massive scale of this test and app will allow tens of millions of people to have access to rapid and reliable testing,” said Joseph Petrosino, PhD, professor and chairman, Molecular Virology and Microbiology, Baylor College of Medicine, in the Abbott news release. “With lab-based tests, you get excellent sensitivity but might have to wait days or longer to get the results. With a rapid antigen test, you get a result right away, getting infectious people off the streets and into quarantine so they don’t spread the virus.”
Abbott has invested hundreds of millions of dollars in two manufacturing facilities where the tests will be made, John Hackett Jr, PhD, an immunologist and Abbott’s Divisional Vice President Applied Research and Technology, and lead scientist on the BinaxNOW project, told The Atlantic.
“Our nation’s frontline healthcare workers and clinical laboratory personnel have been under siege since the onset of this pandemic,” said Charles Chiu, MD, PhD, professor of Laboratory Medicine at University of California, San Francisco, in the Abbott news release. “The availability of rapid testing for COVID-19 will help support overburdened laboratories, accelerate turnaround times, and greatly expand access to people who need it.”
However, other experts are not so sure. In the Atlantic article, Michael Mina MD, PhD, Assistant Professor Epidemiology at Harvard’s T.H. Chan School of Public Health, voiced the need to test both asymptomatic and pre-symptomatic people. “This is the type of [COVID-19] test we have been waiting for—but may not be the test.”
Nevertheless, the federal government’s investment is significant. Abbott plans to start shipping tens of millions of tests in September and produce 50 million tests per month starting in October, Forbes reported.
Shifting Clinical Laboratory Paradigms
BinaxNOW will be performed without doctors’ orders, in a variety of locations, and results go directly to patients’ smartphone—without a pathologist’s interpretation and medical laboratory report. This is new ground and the impact on non-CLIA labs, and on healthcare in general, is yet to be seen.
Clinical laboratory managers will want to monitor the rise of rapid-response tests that can be easily accessed, conducted, and reported on without physician input.
Pooled testing could become a critical tool for clinical laboratories to spot the SARS-CoV-2 coronavirus among asymptomatic and pre-symptomatic individuals
COVID-19 testing for individuals has expanded in the US, but the number of people actually tested remains a small proportion of the country’s total population and clinical laboratory testing supply shortages continue to hamper progress. A technique known as pooled testing may help. Federal experts hope it will substantially increase the number of individuals who are tested for the SARS-CoV-2 coronavirus before it makes a possible resurgence in the fall.
One-by-one, some of the nation’s largest clinical laboratory organizations are developing the capability to do pooled testing. For example, on July 18, the Food and Drug Administration (FDA) announced it had issued Quest Diagnostics (NYSE:DGX) an Emergency Use Authorization (EUA) for its SARS-CoV-2 rRT-PCR test, and that it is valid for up to four individual samples as a pooled test.
Quest’s rRT-PCR test was the first COVID-19 diagnostic test to be authorized for use with pooled samples, the FDA noted in a new release.
In the FDA’s statement announcing Quest’s EUA for its rRT-PCR test, Stephen M. Hahn, MD (above), FDA Commissioner, said, “This EUA for sample pooling is an important step forward in getting more COVID-19 tests to more Americans more quickly while preserving testing supplies.” He added, “Sample pooling becomes especially important as infection rates decline and we begin testing larger portions of the population.” (Photo copyright: CBS News.)
Following the announcement of Quest’s EUA, on July 24 the FDA announced LabCorp’s (NYSE:LH) EUA for its COVID-19 real-time reverse transcription polymerase chain reaction (rRT-PCR) test. The test, the EUA states, is intended for the “qualitative detection of nucleic acid from SARS-CoV-2 in upper and lower respiratory specimens” in individuals suspected of COVID-19, using “a matrix pooling strategy (i.e., group pooling strategy), containing up to five individual upper respiratory swab specimens (nasopharyngeal, mid-turbinate, anterior nares or oropharyngeal swabs) per pool and 25 specimens per matrix.”
Exponentially Increasing Testing
In pooled testing, instead of performing a coronavirus test on every specimen received by a clinical laboratory, samples from each individual specimen are taken and then combined with samples from other specimens. A single test is then performed on the entire collection of specimen samples.
If the results of the pooled samples are negative for coronavirus, it is safe to assume that all the specimens in the batch are negative for the virus. If the pooled sample comes back positive, then it will be necessary to go back to the original specimens in that pooled sample and test each specimen individually.
In an exclusive interview with Dark Daily’s sister print publication The Dark Report, Steven H. Hinrichs, MD, Chair of the Department of Pathology and Microbiology at the University of Nebraska Medical Center (UNMC), noted that one pitfall of pooled testing is that it works best in areas of low virus prevalence.
“For pooled testing, the ideal level of low prevalence would be an infection rate below 10%,” he said, adding, “For COVID-19 test manufacturers, pooled testing has the potential to reduce the number of standard tests labs run by roughly 40% to 60%, depending on the population being tested.
“Cutting the number of COVID-19 tests would be a disadvantage for test manufacturers, because pooled tests would identify large numbers of uninfected individuals who would not require standard testing with EUA tests.
“On the other hand, this policy would be a significant advantage for US labs because pooled testing would cut the number of standard tests,” he continued. “Clinical labs would save money on tests, reagents, and other supplies. It would also ease the burden on the lab’s technical staff,” Hinrichs concluded.
“In our study, we show that it’s reasonable to pool five samples, although we realized that some people may want to pool 10 samples at once,” noted Hinrichs. “But even if one sample is positive in a pool of five, then testing five samples at once saves 80% of our costs if all of those samples are negative. But, if one sample is positive, each of those five samples needs to be retested using the standard test,” Hinrichs explained.
During an American Society for Microbiology (ASM) virtual conference, Deborah Birx, MD, White House Coronavirus Response Coordinator, said, “Pooling would give us the capacity to go from a half a million tests per day to potentially five million individuals tested per day,” STAT reported.
Advantages of using pooled testing for the coronavirus include:
Expanding the number of individuals tested,
Stretching laboratory supplies, and
Reducing the costs associated with testing.
Health officials believe that individuals who have COVID-19 and are asymptomatic are largely responsible for the rising number of coronavirus cases in the US, STAT reported.
“It allows you to test more frequently in a population that may have a low prevalence of disease,” Benjamin Pinsky, MD, PhD, Associate Professor, Departments of Pathology and Medicine at Stanford University School of Medicine, told STAT. “That would allow you to test a lot of negatives, but also identify individuals who are then infected, before they develop symptoms.”
Pooled testing also could be advantageous for communities where COVID-19 is not prevalent, in neighborhoods that need to be tested during an outbreak, and for schools, universities, organizations, and businesses that want to remain safely open while periodically monitoring individuals for the virus, CNN reported.
“The goal is to increase the capacity of testing in a relatively straightforward fashion,” Pinsky told STAT. “The caveat is that by pooling the sample, you’re going to reduce the sensitivity of the test.”
According to Pinsky, “pooling only makes sense in places with low rates of COVID-19, where you expect the large majority of tests to be negative. Otherwise, too many of the pools would come back positive for it to work as a useful surveillance tool,” STAT reported.
As Clinical Lab Testing Increases, Pooled Testing for COVID-19 Could Be Critical
Pooled testing has been used in other countries, including China, to test larger amounts of people for COVID-19.
“If you look around the globe, the way people are doing a million tests or 10 million tests is they’re doing pooling,” Birx said during the ASM virtual conference, CNN reported.
In a press release, the American Clinical Laboratory Association (ACLA) stated that about 300,000 tests for COVID-19 were performed per day in labs across the US in late June. That number was up from approximately 100,000 tests being performed daily in early April.
“All across the country, clinical laboratories are increasing the number of labs processing tests, purchasing additional testing platforms, and expanding the number of suppliers to provide critical testing materials,” said Julie Khani, ACLA President in the press release. “However, the reality of this ongoing global pandemic is that testing supplies are limited. Every country across the globe is in need of essential testing supplies, like pipettes and reagents, and that demand is likely to increase in the coming months.”
Clinical laboratory managers will want to keep an eye on these developments. As the need for COVID-19 testing increases, pooled testing may provide an efficient, cost-effective way to spot the coronavirus, especially among those who are asymptomatic or pre-symptomatic and who display no symptoms.
Pooled testing could become a critical tool in the diagnosis of COVID-19 and potentially decrease the overall number of deaths.
