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Rapid antigen test

A rapid antigen test (RAT), sometimes called a rapid antigen detection test (RADT), antigen rapid test (ART), or loosely just a rapid test, is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. RATs are a type of lateral flow test detecting antigens, rather than antibodies (antibody tests) or nucleic acid (nucleic acid tests). Rapid tests generally give a result in 5 to 30 minutes, require minimal training or infrastructure, and have significant cost advantages.[citation needed] Rapid antigen tests for the detection of SARS-CoV-2, the virus that causes COVID-19, have been commonly used during the COVID-19 pandemic.

Rapid antigen test
SynonymsRapid antigen detection test (RADT), lateral flow test, lateral flow device, rapid test, Antigen rapid test
PurposeTo diagnose infections
A COVID-19 Rapid Antigen test(top) with a Covid-19 Rapid Antigen and a Influenza A&B Rapid Antigen Test(bottom)

For many years, an early and major class of RATs—the rapid strep tests for streptococci—were so often the referent when RATs or RADTs were mentioned that the two latter terms were often loosely treated as synonymous with those. Since the COVID-19 pandemic, awareness of RATs is no longer limited to health professionals and COVID-19 has become the expected referent, so more precise usage is required in other circumstances.

RATs are based on the principle of antigen-antibody interaction. They detect antigens (generally a protein on the surface of a virus). A linear chromatography substrate (a porous piece of material) bears an indicator line, onto which antibodies directed against the target antigen are fixed. Antibodies are also fixed to a visualisation marker (generally a dye, though sometimes these antibodies are modified to fluoresce), to which the sample is added. Any virus particles present will bind to these markers. This mix then travels through the substrate through capillarity. When it reaches the indicator line, virus particles are immobilised by the antibodies fixed there, along with the visualisation marker, allowing concentration and thus visual detection of significant levels of virus in a sample.[1]

A positive result with an antigen test should generally be confirmed by RT-qPCR or some other test with higher sensitivity and specificity.[1]

Uses edit

Common examples of RATs or RADTs include:

COVID-19 rapid antigen tests edit

 
SARS-CoV-2 rapid tests showing a negative and a positive result

Rapid antigen tests for COVID-19 are one of the most useful applications of these tests. Often called lateral flow tests, they have provided global governments with several benefits. They are quick to implement with minimal training, offered significant cost advantages, costing a fraction of existing forms of PCR testing and give users a result within 5–30 minutes. Rapid antigen tests have found their best use as part of mass testing or population-wide screening approaches.[3] They are successful in these approaches because in addition to the aforementioned benefits, they identify individuals who are the most infectious and could potentially spread the virus to a large number of other people.[4] This differs slightly from other forms of COVID-19 tests such as PCR that are generally seen to be a useful test for individuals.[citation needed]

As early as February 2021, the US Department of State considered the antigen test suitable for entry to the country.[5] In Canada, although the antigen test appeared to be no route to entry in January 2021,[6] Health Canada in August 2021 made available subsidized at no cost rapid antigen tests "to more small and medium-sized organizations through new pharmacy partners".[7]

Scientific basis and underlying biology edit

RATs are immunochromatographic assays which give results that can be seen with the naked eye (with or without special illumination, such as a UV lamp). They are qualitative in nature, although within a certain range it is possible to make rough order of magnitude estimates of viral load from the results. RATs are generally screening tests, with relatively low sensitivity and specificity, thus results should be evaluated on the basis of confirmatory tests like PCR testing or western blot.[citation needed]

One inherent advantage of an antigen test over an antibody test (such as antibody-detecting rapid HIV tests) is that it can take time for the immune system to develop antibodies after infection begins, but the foreign antigen is present right away. Although any diagnostic test may have false negatives, this latency period can open an especially wide avenue for false negatives in antibody tests, although the particulars depend on which disease and which test are involved. A rapid antigen test typically costs around US$5 to manufacture.[citation needed]

References edit

  1. ^ a b "SARS-CoV-2 (Covid-19): Rapid Antigen Test for Diagnosis Biotrend". www.biotrend.com. Retrieved 2022-03-16.
  2. ^ Stewart EH, Davis B, Clemans-Taylor BL, Littenberg B, Estrada CA, Centor RM (2014-11-04). "Rapid antigen group A streptococcus test to diagnose pharyngitis: a systematic review and meta-analysis". PLOS ONE. 9 (11): e111727. Bibcode:2014PLoSO...9k1727S. doi:10.1371/journal.pone.0111727. PMC 4219770. PMID 25369170.
  3. ^ "Press corner". European Commission – European Commission. Retrieved 2021-03-20.
  4. ^ Guglielmi G (September 2020). "Fast coronavirus tests: what they can and can't do". Nature. 585 (7826): 496–498. Bibcode:2020Natur.585..496G. doi:10.1038/d41586-020-02661-2. PMID 32939084. S2CID 221768935.
  5. ^ "COVID-19 Testing Required for U.S. Entry". U.S. Department of State. 12 February 2021. Retrieved 3 August 2021.
  6. ^ Pihach, Michael (25 January 2021). "Why does Canada accept PCR (instead of antigen) tests? Health Canada explains". PAXGlobalmedia.
  7. ^ "Government of Canada makes rapid antigen tests available to more small and medium-sized organizations through new pharmacy partners". Verizon Media. yahoo! finance. 14 August 2021.

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A rapid antigen test RAT sometimes called a rapid antigen detection test RADT antigen rapid test ART or loosely just a rapid test is a rapid diagnostic test suitable for point of care testing that directly detects the presence or absence of an antigen RATs are a type of lateral flow test detecting antigens rather than antibodies antibody tests or nucleic acid nucleic acid tests Rapid tests generally give a result in 5 to 30 minutes require minimal training or infrastructure and have significant cost advantages citation needed Rapid antigen tests for the detection of SARS CoV 2 the virus that causes COVID 19 have been commonly used during the COVID 19 pandemic Rapid antigen testSynonymsRapid antigen detection test RADT lateral flow test lateral flow device rapid test Antigen rapid testPurposeTo diagnose infectionsA COVID 19 Rapid Antigen test top with a Covid 19 Rapid Antigen and a Influenza A amp B Rapid Antigen Test bottom For many years an early and major class of RATs the rapid strep tests for streptococci were so often the referent when RATs or RADTs were mentioned that the two latter terms were often loosely treated as synonymous with those Since the COVID 19 pandemic awareness of RATs is no longer limited to health professionals and COVID 19 has become the expected referent so more precise usage is required in other circumstances RATs are based on the principle of antigen antibody interaction They detect antigens generally a protein on the surface of a virus A linear chromatography substrate a porous piece of material bears an indicator line onto which antibodies directed against the target antigen are fixed Antibodies are also fixed to a visualisation marker generally a dye though sometimes these antibodies are modified to fluoresce to which the sample is added Any virus particles present will bind to these markers This mix then travels through the substrate through capillarity When it reaches the indicator line virus particles are immobilised by the antibodies fixed there along with the visualisation marker allowing concentration and thus visual detection of significant levels of virus in a sample 1 A positive result with an antigen test should generally be confirmed by RT qPCR or some other test with higher sensitivity and specificity 1 Contents 1 Uses 1 1 COVID 19 rapid antigen tests 2 Scientific basis and underlying biology 3 ReferencesUses editCommon examples of RATs or RADTs include COVID 19 testing related rapid tests Rapid strep tests for streptococcal antigens 2 Rapid influenza diagnostic tests RIDTs for influenza virus antigens Malaria antigen detection tests for Plasmodium antigens COVID 19 rapid antigen tests edit Main article COVID 19 rapid antigen test nbsp SARS CoV 2 rapid tests showing a negative and a positive resultRapid antigen tests for COVID 19 are one of the most useful applications of these tests Often called lateral flow tests they have provided global governments with several benefits They are quick to implement with minimal training offered significant cost advantages costing a fraction of existing forms of PCR testing and give users a result within 5 30 minutes Rapid antigen tests have found their best use as part of mass testing or population wide screening approaches 3 They are successful in these approaches because in addition to the aforementioned benefits they identify individuals who are the most infectious and could potentially spread the virus to a large number of other people 4 This differs slightly from other forms of COVID 19 tests such as PCR that are generally seen to be a useful test for individuals citation needed As early as February 2021 the US Department of State considered the antigen test suitable for entry to the country 5 In Canada although the antigen test appeared to be no route to entry in January 2021 6 Health Canada in August 2021 made available subsidized at no cost rapid antigen tests to more small and medium sized organizations through new pharmacy partners 7 Scientific basis and underlying biology editRATs are immunochromatographic assays which give results that can be seen with the naked eye with or without special illumination such as a UV lamp They are qualitative in nature although within a certain range it is possible to make rough order of magnitude estimates of viral load from the results RATs are generally screening tests with relatively low sensitivity and specificity thus results should be evaluated on the basis of confirmatory tests like PCR testing or western blot citation needed One inherent advantage of an antigen test over an antibody test such as antibody detecting rapid HIV tests is that it can take time for the immune system to develop antibodies after infection begins but the foreign antigen is present right away Although any diagnostic test may have false negatives this latency period can open an especially wide avenue for false negatives in antibody tests although the particulars depend on which disease and which test are involved A rapid antigen test typically costs around US 5 to manufacture citation needed References edit a b SARS CoV 2 Covid 19 Rapid Antigen Test for Diagnosis Biotrend www biotrend com Retrieved 2022 03 16 Stewart EH Davis B Clemans Taylor BL Littenberg B Estrada CA Centor RM 2014 11 04 Rapid antigen group A streptococcus test to diagnose pharyngitis a systematic review and meta analysis PLOS ONE 9 11 e111727 Bibcode 2014PLoSO 9k1727S doi 10 1371 journal pone 0111727 PMC 4219770 PMID 25369170 Press corner European Commission European Commission Retrieved 2021 03 20 Guglielmi G September 2020 Fast coronavirus tests what they can and can t do Nature 585 7826 496 498 Bibcode 2020Natur 585 496G doi 10 1038 d41586 020 02661 2 PMID 32939084 S2CID 221768935 COVID 19 Testing Required for U S Entry U S Department of State 12 February 2021 Retrieved 3 August 2021 Pihach Michael 25 January 2021 Why does Canada accept PCR instead of antigen tests Health Canada explains PAXGlobalmedia Government of Canada makes rapid antigen tests available to more small and medium sized organizations through new pharmacy partners Verizon Media yahoo finance 14 August 2021 Retrieved from https en wikipedia org w index php title Rapid antigen test amp oldid 1187998635, wikipedia, wiki, book, books, library,

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