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| An antigen is a substance—often a protein but may also be an environmental like a virus—that provokes the immune system to produce an antibody against it.<ref name="MPAntigen">{{cite web |url=https://medlineplus.gov/ency/article/002224.htm |title=Antigen |work=MedlinePlus |publisher=U.S. National Library of Medicine |accessdate=07 August 2020}}</ref> As such, another approach to testing for the presence of a virus in a specimen is to test for the antigen rather than the antibody. An antigen test is useful as a repeated surveillance test, but it has drawbacks as a one-time diagnostic test.<ref name="Anderson5Invest20">{{cite web |url=https://www.wcvb.com/article/5-investigates-concerns-about-current-use-of-rapid-antigen-tests-for-covid-19/33538332 |title=5 Investigates: Concerns about current use of rapid antigen tests for COVID-19 |author=Anderson, K. |work=WCVB 5 ABC |date=06 August 2020 |accessdate=07 August 2020}}</ref><ref name="ServiceRadical2020">{{cite journal |title=Radical shift in COVID-19 testing needed to reopen schools and businesses, researchers say |journal=Science |author=Service, R.F. |year=2020 |doi=10.1126/science.abe1546}}</ref><ref name="KremerUWSys20">{{cite web |url=https://urbanmilwaukee.com/2020/08/07/uw-system-orders-350000-covid-19-tests/ |title=UW System Orders 350,000 COVID-19 Tests |author=Kremer, R. |work=Urban Milwaukee |date=07 August 2020 |accessdate=07 August 2020}}</ref> For COVID-19 and other viral infections, an antigen test has the advantage that specimen collection can typically be done with a simple nasal swab rather than a more invasive [[nasopharyngeal swab]]. Another advantage, on one hand, is that antigen testing is more rapid and convenient because the extraction and amplification steps of PCR are not used. On the other, antigen testing is less sensitive for the same reason: you test only what's there (rather than amplifying the amount for greater sensitivity).<ref name="ServiceRadical2020" /><ref name="GuglielmiTheExp20">{{cite journal |title=The explosion of new coronavirus tests that could help to end the pandemic |journal=Nature |author=Guglielmi, G. |volume=583 |pages=506–09 |year=2020 |doi=10.1038/d41586-020-02140-8}}</ref>
| | {{Saved book |
| | |title=Introduction to Quality and Quality Management Systems |
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| A theory increasingly gaining traction, however, is that "[a] higher frequency of testing makes up for poor sensitivity.”<ref name="ServiceRadical2020" /><ref name="KremerUWSys20" /><ref name="ClarkCOVID20">{{cite web |url=https://www.medpagetoday.com/infectiousdisease/covid19/87930 |title=COVID Antigen Tests: Coming to Case Counts Near You? |author=Clark, C. |work=MedPage Today |date=06 August 2020 |accessdate=07 August 2020}}</ref> Several researchers have shared pre-print and published research suggesting this outcome<ref name="ServiceRadical2020" />:
| | ==''Introduction to Quality and Quality Management Systems''== |
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| | | text = This book should not be considered complete until this message box has been removed. This is a work in progress. |
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| | The goal of this short volume is to act as an introduction to the quality management system. It collects several articles related to quality, quality management, and associated systems. |
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| <blockquote>Larremore and his colleagues have modeled the benefits of more frequent tests, even ones that are less accurate than today’s. Fast tests repeated every three days, with isolation of people who test positive, prevents 88% of viral transmission compared with no tests; a more sensitive test used every two weeks reduced viral transmission by about 40%, they report in a 27 June preprint on medRxiv. Paltiel and his colleagues reached much the same conclusion when they modeled a variety of testing regimes aimed at safely reopening a 5000-student university. In a 31 July paper in JAMA Network Open, they found that, with 10 students infected at the start of the semester, a test that identified only 70% of positive cases, given to every student every two days, could limit the number of infections to 28 by the end of the semester. Screening every seven days allowed greater viral spread, with the model predicting 108 infections.</blockquote>
| | ;1. What is quality? |
| | :''Key terms'' |
| | :[[Quality (business)|Quality]] |
| | :[[Quality assurance]] |
| | :[[Quality control]] |
| | :''The rest'' |
| | :[[Data quality]] |
| | :[[Information quality]] |
| | :[[Nonconformity (quality)|Nonconformity]] |
| | :[[Service quality]] |
| | ;2. Processes and improvement |
| | :[[Business process]] |
| | :[[Process capability]] |
| | :[[Risk management]] |
| | :[[Workflow]] |
| | ;3. Mechanisms for quality |
| | :[[Acceptance testing]] |
| | :[[Conformance testing]] |
| | :[[Clinical quality management system]] |
| | :[[Continual improvement process]] |
| | :[[Corrective and preventive action]] |
| | :[[Good manufacturing practice]] |
| | :[[Malcolm Baldrige National Quality Improvement Act of 1987]] |
| | :[[Quality management]] |
| | :[[Quality management system]] |
| | :[[Total quality management]] |
| | ;4. Quality standards |
| | :[[ISO 9000]] |
| | :[[ISO 13485]] |
| | :[[ISO 14000|ISO 14001]] |
| | :[[ISO 15189]] |
| | :[[ISO/IEC 17025]] |
| | :[[ISO/TS 16949]] |
| | ;5. Quality in software |
| | :[[Software quality]] |
| | :[[Software quality assurance]] |
| | :[[Software quality management]] |
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| As such, the utility of antigen testing, despite its lower sensitivity, appears to be surveillance situations where a large group of individuals who are at risk can be screened at regularly scheduled intervals of two to four days. The end result, in theory, would be few people who are target-positive would be missed, positives could be isolated and verified with a more sensitive test, and more target-positive people would be identified and isolated before reaching peak infectivity.<ref name="ServiceRadical2020" /><ref name="CourageCovid20">{{cite web |url=https://www.vox.com/2020/7/31/21336212/covid-19-test-results-delays |title=Should we be testing fewer people to stop the spread of Covid-19? |author=Courage, K.H. |work=Vox |date=31 July 2020 |accessdate=05 August 2020}}</ref> To be clear, it's not a perfect solution, but as Harvard epidemiologist Michael Mina and Boston University economist Laurence Kotlikoff suggest, "[w]e need the best means of detecting and containing the virus, not a perfect test no one can use."<ref name="CourageCovid20" /> In August 2020, a coalition of six U.S. state governors bought into that concept and agreed to work together with the Rockefeller Foundation, as well as the Quidel Corporation and Becton, Dickinson and Company, which had received FDA EUAs to market antigen tests for SARS-CoV-2.<ref name="ClarkCOVID20" /><ref name="MervoshItsLike20">{{cite web |url=https://www.nytimes.com/2020/08/04/us/virus-testing-delays.html |title=‘It’s Like Having No Testing’: Coronavirus Test Results Are Still Delayed |author=Mervosh, S.; Fernandez, M. |work=The New York Times |date=04 August 2020 |accessdate=05 August 2020}}</ref> As of September 2021, thirty-four FDA EUAs for antigen tests have been issues; 28 of those 34 include allowances for CLIA-waived testing, and 10 were authorized for home use.<ref name="FDAInVitroAntigen21">{{cite web |url=https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/in-vitro-diagnostics-euas-antigen-diagnostic-tests-sars-cov-2 |title=In Vitro Diagnostics EUAs - Antigen Diagnostic Tests for SARS-CoV-2 |publisher=U.S. Food and Drug Administration |date=07 September 2021 |accessdate=07 September 2021}}</ref>
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| ==References==
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| {{Reflist|colwidth=30em}}
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