Rapid Antigen vs RTPC Test
No Comments
Subject: Science and tech
Context:
Indian Council of Medical Research (ICMR) approved new kind of test for diagnosis of Covid-19 called rapid antigen detection test
Concept:
- The test is done on swabbed nasal samples that detect 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.
RT-PCR vs Rapid antigen test:
- RT-PCR is currently the gold standard frontline test for the diagnosis of Covid-19.
- Like RT-PCR, the rapid antigen detection test too seeks to detect the virus rather than the antibodies produced by the body.
- While the mechanism is different, 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 reliable rapid antigen detection test, the maximum duration for interpreting a positive or negative test is 30 minutes.
Concern:
- US FDA pointed out that antigen 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.
- As of now, the kit will be used in containment zones or hotspots and healthcare settings.