NEW YORK ─ Processing of thousands of antigen tests per day on machines located in laboratories may be a more powerful way to help stem the pandemic than doing rapid antigen tests for SARS-CoV-2 one after another at the point of care, according to some diagnostic industry insiders.
To meet escalating test demand, healthcare providers need to run antigen assays on high-throughput instruments that are already broadly available in laboratories worldwide, said Chockalingam Palaniappan, chief innovation officer at Ortho Clinical Diagnostics, which recently obtained CE marking for such a test.
The Raritan, New Jersey-based diagnostic company received the designation for its Vitros SARS-CoV-2 Antigen test, enabling its use in Europe and other regions that recognize the CE mark.
Ortho has also submitted an Emergency Use Authorization request for its high-throughput antigen assay to the US Food and Drug Administration that it expects could issue "within weeks, not months," Palaniappan said.
The company has the capacity to enable laboratories to run around five million tests per day in the US alone, he added.
A third wave of infections surfacing in various regions worldwide points to a clear need for population-level testing that is intermittently repeated for each person taking a test for as long as the pandemic is here, Palaniappan said, adding, "That is not logistically possible using current PCR methodologies and point-of-care antigen tests."
However, laboratories using high-throughput machines, capable of running thousands of antigen tests per day, are returning test results within 24 hours of getting a sample, far faster than most RT-PCR lab tests, he said.
Ortho's CE mark allows for testing people that show symptoms of SARS-CoV-2, and the firm's EUA application covers such symptomatic testing. However, the company is also pursuing authorizations in the US, Europe, and elsewhere to test people who are asymptomatic in a bid to further help mitigate the pandemic, according to Palaniappan. Â Â
Overall, he said, Ortho believes that its high-throughput antigen tests have the potential to complement RT-PCR testing for active infections while providing faster turnaround times and helping mitigate supply-chain challenges that have been a drag on the availability of molecular tests.
"The need is immense for getting people back to colleges and schools and to manufacturing facilities and companies where large numbers of people need screening, and that's where these tests come into play," he said.
Other diagnostic industry players have said that they are launching high-throughput antigen testing for similar reasons.
For example, DiaSorin recently announced that it has also received CE marking for an antigen assay. Its Liaison SARS-CoV-2 Ag test is a chemiluminescence immunoassay that detects the coronavirus nucleocapsid protein antigen in nasal dry swabs and nasopharyngeal swabs eluted in universal transport media used for the virus.Â
The company has 8,000 systems able to run the assay installed in laboratories worldwide and intends to apply for an FDA EUA.
DiaSorin has allocated capacity to manufacture up to 10 million Liaison SARS-CoV-2 Ag tests per month soon after launch that can deliver up to 140 test results per hour. However, a DiaSorin spokesperson added that market demand will ultimately decide how many tests it manufactures.
"We should also not forget that COVID-19 is a global pandemic and while some markets are able to acquire the volumes of testing needed to use PCR as a monitoring tool and pay the price tag of these tests, there are many countries where antigen testing can provide an additional tool to fight the pandemic," the spokesperson said.Â
Additionally, Roche has announced plans to launch a high-volume laboratory-based SARS-CoV-2 Antigen test toward the end of this year for regions accepting the CE mark, and it also intends to file for an FDA EUA.
Its Elecsys SARS-CoV-2 Antigen assay, which detects the nucleocapsid antigen of SARS-CoV-2, is performed by healthcare professionals and uses nasopharyngeal or oropharyngeal swab samples while running on the firm's Cobas e immunochemistry analyzers. Depending on the analyzer, a throughput of up to 300 tests per hour is possible, the company said.
A spokesperson for Basel, Switzerland-based Roche told 360Dx that its goal is to "ramp up to double-digit million tests per month in early 2021 to match the testing demands of healthcare systems globally."
Like Ortho, Roche sees high-throughput antigen testing as a modality that can boost the supply of platforms and assays for active infection testing. "Due to the current global limitations in the available capacity and accessibility of high-throughput RT-PCR testing, a highly accurate alternative diagnostic test for SARS-CoV-2 infection is needed to guide action for isolation and clinical care of SARS-CoV-2-infected individuals," the spokesperson said. Â
Roche believes the Elecsys SARS-CoV-2 Antigen assay will enable more efficient testing and consolidation with other markers used as part of diagnostic assessment of SARS-CoV-2 infected patients, and it said its laboratory-based assay enables cost and error reduction by eliminating manual handling.
"High-throughput antigen testing in a central lab can compete favorably with point-of-care testing done at the site of collection both on cost and in overall turnaround time for the population," Robert Boorstein, medical director at Brooklyn-based Lenco Diagnostic Laboratory, said in an interview. "Just because an antigen test can be done at the point of care doesn’t mean that an organization ─ a school, nursing home, work site, [or other such setting] ─ has the desire or resources to do point-of-care testing in high volumes. They may lack the personnel to run the tests, report the results, maintain inventory, and do mandatory state reporting."
And there are additional reasons for lab directors to want to do high-throughput antigen testing. "From our perspective, labs will offer what doctors want and what payors pay for," Boorstein said. "If payors define classes of patients for whom they will only pay for antigen testing, labs will provide antigen testing for those patients. As a precedent, we have insurers that will not cover molecular testing for flu but will pay for antigen testing."
Rapid Testing
Rapid antigen tests are also inexpensive and each test can be done quickly ─ sometimes within 15 minutes ─ which adds to their appeal. Many observers believe such tests also provide a way to help mitigate slow turnaround times and supply chain bottlenecks encountered in RT-PCR testing.
In addition to its high-throughput antigen test, Roche has announced plans to launch its SARS-CoV-2 Rapid Antigen Test, an instrument-free test. The rapid assay "enables fast decision making and can facilitate early implementation of infection control measures in decentralized settings," the Roche spokesperson said. "The test helps to expand the range and quantity of direct virus testing into otherwise inaccessible settings and allows testing, [for example], in rural [and] low-infrastructure areas."
The potential for antigen tests led the governors of six US states to announce in August they were in discussions with Becton Dickinson and Quidel to purchase 500,000 rapid tests per state. And a month later, President Trump announced the planned national distribution of 150 million of the Abbott Laboratories' BinaxNow COVID-19 Ag Card, a low-cost, point-of-care SARS-CoV-2 antigen test that does not require an analyzer, and is one of seven antigen tests that the FDA has authorized for use during the pandemic.
Though point-of-care antigen tests can provide a fast turnaround, concerns have surfaced about the levels of accuracy for some of them. None so far have shown the level of performance of RT-PCR tests and, recently, the FDA released a letter warning laboratories and healthcare providers about the potential for false-positive results with rapid antigen tests for detecting SARS-CoV-2.
In a research note on Wednesday, BTIG research analyst Mark Massaro said that an expert panel of US-based lab directors noted that keeping up with test demand continues to be challenging during the pandemic, and all directors were experiencing a current second or third wave associated with a surge in demand.
"Access to rapid antigen tests remains limited, and one director noted that antigen tests are not sensitive and highly questions the clinical utility in this outbreak," Massaro added.
Ortho said its high-throughput antigen test has demonstrated 97.8 percent sensitivity and 99.2 percent specificity. The test has further demonstrated 100 percent sensitivity at PCR cycle thresholds of less than 32 and 97.8 percent sensitivity at PCR cycle thresholds of less than 34, levels above which many observers believe people may no longer be infectious, Palaniappan said.
Meanwhile, DiaSorin has said that its high-throughput assay demonstrated 97.1 percent sensitivity and 100 percent specificity on nasal swabs and 94.6 percent sensitivity and 99.5 percent specificity on nasopharyngeal swabs used within 10 days of the onset of COVID-19 symptoms.
Manufacturing capacity
But just as important as making antigen tests available is having the capacity to satisfy high demand.
With 1,500 Vitros instruments already in the market in about 1,000 hospitals and each instrument running up to 3,500 tests per day, Ortho could satisfy demand for more than 5 million tests per day in the US alone, Palaniappan said. The company said it has around 5,000 such instrument placements globally.
The diagnostic company also has two types of antibody assays on the market that are authorized to test for SARS-CoV-2 Â past infection. One detects total antibodies to SARS-CoV-2 and the other detects IgG antibodies, and both have received CE marking and FDA EUA.
However, Ortho doesn't manufacture RT-PCR tests, the most broadly adopted testing modality during the pandemic. Palaniappan did not respond directly to a question about how that has impacted the firm's business.
The company has shipped millions of its antibody tests globally during the pandemic, he said, adding that with its antigen assay running on the same instruments as its antibody assays, customers can now tap into both modalities in the same laboratory setting.
Serology tests for past infections have taken a back seat to RT-PCR and antigen testing for active infections during the pandemic, but demand for antibody tests is expected to rise with the availability of vaccines and with clinicians needing a way to monitor levels of antibodies in people who have been vaccinated.