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Rapid antigen test

Topics Covered: Issues related to health.

Rapid antigen test

The Context:

The Indian Council of Medical Research (ICMR) has recommended the use of Standard Q COVID-19 Ag antigen detection test in containment zones and healthcare settings in combination with the RT-PCR test.

The is to be used in specified settings, and kits from only one manufacturer have got approval– the South Korean company S D Biosensor.

What are antigens?

Antigens are foreign substances that induce an immune response in the body.

What is the rapid antigen detection test for Covid-19?

It is a test on swabbed nasal samples that detects antigens that are found on or within the SARS-CoV-2 virus.

It is a point-of-care test, performed outside the conventional laboratory setting, and is used to quickly obtain a diagnostic result.

How is rapid antigen detection test different from RT-PCR test?

Like RT-PCR, the rapid antigen detection test too seeks to detect the virus rather than the antibodies produced by the body.

The most significant difference between the two is time.

  • RT-PCR test takes a minimum of 2-5 hours including the time taken for sample transportation.
  • In a rapid antigen detection test, the maximum duration for interpreting a positive or negative test is 30 minutes.

What are the limitations of an antigen test’s results?

  1. These tests are very specific for the virus, but are not as sensitive as molecular PCR tests. This means that positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection.
  2. Negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative.
  3. Once the sample is collected in the extraction buffer, it is stable only for one hour. Therefore, the antigen test needs to be conducted at the site of sample collection in the healthcare setting.

InstaLinks:

Prelims Link:

  1. Differentiate between- RT- PCR, Rapid antibody and rapid antigen tests.
  2. What are antibodies?
  3. Wha are antigens?
  4. How body’s immune system works?
  5. What are lymphocytes?
  6. Coronavirus that affect humans.

Mains Link:

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Sources: Indian Express.