Adaptive Biotechnologies Gets FDA Authorization for SARS-CoV-2 T Cell Response Test
The Food and Drug Administration (FDA) has issued an emergency use authorization for the T-Detect COVID test developed by Adaptive Biotechnologies. This test uses next-generation sequencing to analyze DNA sequences from T cells to help identify individuals with an adaptive T cell immune response to SARS-CoV-2. A positive test result indicates recent or prior infection with SARS-CoV-2, while a negative test result indicates that a patient is unlikely to have been infected with the virus. However, negative results do not preclude acute or current SARS-CoV-2 infection, and the test should not be used to diagnose current SARS-CoV-2 infection.
A T cell response may be detected in the blood several days after initial infection, and the T-Detect COVID test is indicated for use with samples from individuals who are 15 days or more postsymptom onset. However, in a statement about the test, FDA noted
that it is unknown how long the T cell immune response persists following infection and what level of protection it may provide.
Currently, use of the T-Detect COVID test is limited to laboratories designated by Adaptive Biotechnologies that are certified under CLIA and that meet
the requirements to perform high complexity tests.
FDA OKs Abbott’s Rapid SARS-CoV-2 Antigen Test for Over-the-Counter Use
Abbott has received Food and Drug Administration emergency use authorization for over-the-counter use of its BinaxNOW COVID-19 Ag self test. This new indication allows individuals with or without symptoms to buy the test without a prescription. As of April, Abbott planned to ship the test to major food, drug, and mass merchandising retailers and expected the test to eventually be available through some of these stores’ websites.
Individuals ages 15 years or older can use BinaxNOW with self-collected samples, and the test also can be used on children as young as 2 years old when samples are collected by an adult. Samples are collected using a nasal swab, and all materials required to perform the test, such as the swab, test card, and reagent solution, come in the box. The test produces results in 15 minutes, enabling individuals who test positive to immediately isolate themselves. The BinaxNOW self test also comes in a two-count box so that users can perform serial testing.
Roche SARS-CoV-2, Flu Combo Test Could Give False Positive Results, FDA Warns
The Food and Drug Administration (FDA) has issued a letter alerting clinical laboratory staff, point-of-care facility staff, and healthcare providers that false-positive results can occur with the Roche cobas SARS-CoV-2 & Influenza A/B nucleic acid test, which is designed for use on the cobas Liat system. Roche has observed two different issues with this test that could cause false positives. The first issue is that the assay tubes may leak sporadically, obstructing the optical path in the Liat analyzer and producing abnormal polymerase chain reaction (PCR) growth curves. The second issue is that abnormal PCR cycling in the reaction tubes may also occur and produce abnormal PCR growth curves.
In light of these potential issues, FDA recommends that users of the cobas SARS-CoV-2 & Influenza A/B test should monitor for unexpected clusters of positive influenza B results, as this may indicate the cobas Liat system has experienced a tube leak. Additionally, users should repeat tests when two or three analytes are positive. Different results on the repeat test may indicate abnormal PCR cycling. If after following these steps users suspect that either of the two aforementioned issues has occurred, they should stop using the cobas Liat system and contact Roche.
FDA Cautions That Three Cepheid SARS-CoV-2 Tests Could Be Impacted by Variants
In addition to tests from Mesa Biotech, Thermo Fisher Scientific, and Applied DNA Sciences, the Food and Drug Administration (FDA) also has added three tests from Cepheid to its list of SARS-CoV-2 assays that are impacted by variants of the virus. These tests are Cepheid’s Xpert Xpress SARS-CoV-2, Xpert Xpress SARS-CoV-2 DoD, and Xpert Omni SARS-CoV-2. FDA’s analysis indicates that two independent single-point mutations in the SARS-CoV-2 genome reduce these tests’ sensitivity for detecting the N2 gene. When enough virus is present, though, the tests still detect the E gene. Detection of the E gene without detecting the N2 gene is reported as a presumptive positive result by the Xpert Xpress SARS-CoV-2 and Xpert Xpress SARS-CoV-2 DoD tests, and as a positive result by the Xpert Omni SARS-CoV-2.
Overall, since Cepheid’s tests are designed to detect multiple genetic targets and these mutations do not lead to false-negative results, FDA concludes that the impact on test performance does not appear to be significant. However, out of an abundance of caution, the agency still thought it best to alert healthcare professionals about this potential issue.
CE Mark Granted to Bio-Techne’s Exosome Diagnostics for Prostate Liquid Biopsy Test
Exosome Diagnostics, a brand of Bio-Techne Corporation, has received the CE mark for the ExoDx Prostate test (EPI-CE) kit, which is a noninvasive, urine-based genomic test that helps clinicians determine whether or not a patient needs a prostate biopsy. The test is a risk assessment tool and is intended for use when patients have an ambiguous prostate-specific antigen test result. In studies, the EPI-CE test demonstrated comparable results to the Food and Drug Administration-approved version of the test, with a sensitivity of 92% and a negative predictive value of 89% for ruling out clinically significant prostate cancer. By ruling out the need for prostate biopsy, Bio-Techne hopes the test will help reduce complications from this invasive procedure, which can include pain, hematuria, infection, and potentially hospitalization. Now that the test has received the CE mark, Bio-Techne is offering it at the company’s Munich ISO 15189 accredited clinical laboratory and is also making it available throughout Europe.