Saving Lives, Protecting People, Recommendations for healthcare providers using SARS-CoV-2 diagnostic tests for screening asymptomatic individuals for COVID-19. See CDC’s guidance for Quarantine; clinical discretion should determine if and when additional testing is necessary. Some public officials anticipate using the COVID-19 antigen test as a tool for widespread screening, including the screening of asymptomatic people. This may result in a negative antigen test result, while a more sensitive test, such as most NAATs, may return a positive result. © Provided by Birmingham WBRC WBRC For more information, see CMS’ How to Obtain a CLIA Certificatepdf iconexternal icon. I’ve been hearing about a new “antigen test” for COVID-19. To receive email updates about COVID-19, enter your email address: Interim Guidance for Antigen Testing for SARS-CoV-2, Centers for Disease Control and Prevention. All testing for SARS-CoV-2, including antigen testing, depends on the integrity of the specimen, which is affected by procedures for both specimen collection and handling. 7Nucleic acid amplification test; confirm within 48 hours using a NAAT, such as RT-PCR, that has been evaluated against FDA’s reference panel for analytical sensitivity The PCR test checks for the genetic material of the virus detected in a person. See Table 1 for additional information about antigen tests. See FDA’s In Vitro Diagnostics EUAsexternal icon. However, RT-PCR can detect levels of viral nucleic acid that cannot be cultured, suggesting that the presence of viral nucleic acid does not always indicate contagiousness. To help estimate pretest probability, CDC recommends that laboratory and testing professionals who perform antigen testing determine infection prevalence based on a rolling average of the positivity rate of their own SARS-CoV-2 testing over the previous 7–10 days. See the antigen testing algorithm when pretest probability is low, Figure 4, which is excerpted directly from the full antigen testing algorithm in Figure 1. For current information about MIT Medical’s services, please see relevant areas of the MIT Medical website. Antigen and Molecular Tests for COVID-19 The diagnostic testing field for COVID-19 is rapidly evolving, with many tests focused on diagnosing patients with active viral infections. See CDC’s guidance on Testing in Nursing Homes, Quarantine and Isolation, Discontinuation of Isolation for Persons with COVID-19 Not in Healthcare Settings, Discontinuation of Transmission-Based Precautions of Patients in Healthcare Settings, and Return to Work for Healthcare Personnel. New section on processing of antigen tests, reflecting what has been learned on how to minimize the risk of false results. The package insert for these tests includes instructions for handling of the test cartridge/card, such as ensuring it remains in its sealed pouch until immediately before use. When testing a person who is asymptomatic and has had exposure to a person with COVID-19 within the last 14 days, indicating that the pretest probability is moderate, the healthcare provider should confirm a positive antigen test result with an FDA-authorized NAAT. Antibody, Antigen And PCR Tests For COVID-19: Know The Differences : Shots - Health News What types of tests are available for the coronavirus, and how accurate are they? See CDC’s guidance for Quarantine; clinical discretion should determine if and when additional testing is necessary. Laboratories and testing sites should refer to the instructions for use and the package insert that are specific for the test that they are using regarding the use of VTM. Also see information from the Centers for Medicare & Medicaid Services (CMS) on Enforcement discretion for the use of SARS-CoV-2 point-of-care testing on asymptomatic individuals.pdf iconexternal icon. 10Quarantine is necessary. Also see CMS’ Enforcement discretion for the use of SARS-CoV-2 point-of-care testing on asymptomatic individualspdf iconexternal icon. Because of concerns about false positive results when pretest probability is low, a positive antigen test result in this circumstance should be followed by a confirmatory NAAT, recognizing that the person will be tested at a later timepoint in their illness if truly infected. Antigen Testing Algorithm – Low Pretest Probability. See CDC’s Interpreting Results of Diagnostic Tests for additional information on the relationship between pretest probability and the likelihood of positive and negative predictive values. PCR tests, per the FDA, detect the genetic material from the virus—or the virus' RNA—which can help diagnose an active COVID-19 infection. Despite the high specificity of antigen tests, false positive results will occur, especially when used in communities where the prevalence of infection is low – a circumstance that is true for all in vitro diagnostic tests. There are increasing amounts of dataexternal icon to help guide the use of antigen tests as screening tests on asymptomatic persons to detect or exclude COVID-19, or to determine whether a person who previously was diagnosed with COVID-19 remains infectious. A CLIA-certified laboratory or testing site must report antigen test results to the individual or the individual’s healthcare provider according to the instructions for use of the FDA-authorized SARS-CoV-2 in vitro diagnostic device that was used. Table 1 summarizes the differences between NAATs and antigen tests. Rapid antigen tests have found their best use as part of mass testing or population-wide screening approaches. Diagnostic tests can be antigen based (“rapid antigen” tests), which look for protein markers on the outside of the virus, or they can be molecular based (including PCR, LAMP, CRISPR), which look for viral genomic material specific to SARS-CoV-2. Positive viral tests indicate a current infection, while positive antibody tests indicate a prior infection.