Rapid antigen test
Rapid antigen test | |
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infections |
A rapid antigen test (RAT), sometimes called a rapid antigen detection test (RADT), antigen rapid test (ART), or
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
Common 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
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
Scientific basis and underlying biology
RATs are
One inherent advantage of an antigen test over an antibody test (such as antibody-detecting
References
- ^ a b "SARS-CoV-2 (Covid-19): Rapid Antigen Test for Diagnosis Biotrend". www.biotrend.com. Retrieved 2022-03-16.
- PMID 25369170.
- ^ "Press corner". European Commission – European Commission. Retrieved 2021-03-20.
- 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.