IVD firms ready high-throughput antigen tests

2020 06 04 19 23 9275 Lab Virus Bacteria Research 400

Antigen tests for COVID-19 are already an important component of testing for the disease. These tests detect protein or gylanic viral components such as spike proteins. While the accuracy of antigen tests is not as high as molecular tests, they are earning a spot in screening because of their cost and portability.

Bruce Carlson from Kalorama Information.Bruce Carlson from Kalorama Information.

Currently marketed tests are primarily rapid tests performed at the point of care and can be confirmed by polymerase chain reaction (PCR) testing. Several firms now have emergency use authorization (EUA) for rapid antigen tests for COVID-19, and soon a new type of test should be brought to bear: antigen tests on automated systems that can run hundreds of tests per hour. Some of these tests are already marketable in countries that accept the CE Mark.

An antigen test reveals if a person is currently infected with a pathogen such as the SARS-CoV-2 virus. Once the infection has gone, the antigen disappears. Guidance from the U.S. Food and Drug Administration (FDA) indicates that when used for screening, testing in congregate settings may give antigen results that should be considered presumptive.

When the pretest probability is low, as in a population not in the midst of an outbreak, the FDA suggests those persons who receive a positive antigen test should isolate until they can be confirmed by reverse transcription (RT)-PCR.

The increasing consensus is that this interplay between test usage is par for the course. There will likely be no one "perfect" test for COVID-19. Each type of testing has its place.

The place for lab antigen tests could be in their throughput, joined with cost advantages. These systems can run hundreds or thousands of tests per day. The equipment is installed throughout the world and operators are trained.

The following recent developments in the area of high-throughput antigen tests are notable:

  • In October, Roche announced that it would launch the Elecsys SARS-CoV-2 antigen test, an automated laboratory assay running on the cobas e immunochemistry analyzers. The test is performed by healthcare professionals and uses nasopharyngeal or oropharyngeal swab samples from patients with signs and symptoms suggestive of COVID-19 or people with either known or suspected exposure. These fully automated systems can provide test results in 18 minutes for a single test (excluding time for sample collection, transport, and preparation), with a throughput of up to 300 tests per hour.
  • In October, DiaSorin announced that its Liaison SARS-CoV-2 Ag high-throughput antigen test received the CE Mark. The Italian IVD firm said the test runs on its Liaison XL, Liaison XS, and Liaison analyzers, and there are more than 8,000 such systems installed in laboratories worldwide.
  • Sysmex received Japanese marketing approval for its high sensitivity and chemiluminescence enzyme immunoassay (HISCL) SARS-CoV-2 Ag Reagent test kit. The immunoassay is designed to detect SARS-CoV-2 antigens in nasopharyngeal and nasal swab samples. It runs on the company's HISCL-5000 and HISCL-800 automated analyzers, providing results within 17 minutes.
  • Fujirebio Diagnostics announced initiation of clinical testing needed for the submission of its new SARS-CoV-2 Antigen assay for an EUA from the FDA. The company's Lumipulse G SARS-CoV-2 antigen assay will be available for use on the Lumipulse G1200 instrument. Lumipulse G1200 has a throughput of 120 tests per hour and allows laboratory personnel to randomly load samples as needed
  • Ortho Clinical Diagnostics announced that it received the CE Mark for its COVID-19 antibody test, and that the FDA accepted the company's emergency use notification (EUN) for, its new Vitros SARS-CoV-2 Antigen test. Ortho's SARS-CoV-2 antigen test runs on Ortho's Vitros XT 7600 Integrated System, the Vitros 3600 Immunodiagnostic System, and the Vitros 5600 Integrated System. The company cites studies showing that samples with a PCR cycle threshold (CT; a measure of viral load) levels at 30-33 or greater carry little to no live virus, suggesting these patients may no longer be infectious. Compared to PCR, Ortho said its test may be better able to identify individuals with COVID-19 who are infectious because the test is offered with 100% sensitivity with samples with a CT count of less than 34. high-throughput, fully automated Vitros platform from swabs, rather than the blood and body fluid samples typically run by the systems.
  • Quanterix was awarded an $18.2 million phase II contract with the U.S. National Institutes of Health (NIH) through its Rapid Acceleration of Diagnostics (RADx) initiative to accelerate the continued development, scale-up, and deployment of a novel SARS-CoV-2 antigen test based on Quanterix' ultra-sensitive Simoa technology. The company said preliminary results indicate that the test has the potential to enable detection from a variety of sample types including self-collected capillary blood, saliva and nasal swabs. Sample collection, transport, and processing will occur within 24-48 hours using existing sample collection logistics infrastructure through a network of centralized labs.

Bruce Carlson is the publisher of Kalorama Information, part of Science and Medicine Group.

Disclosure: LabPulse.com is a sister company of Kalorama Information.

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