Wednesday, 12 August 2020

COVID-19-What is Rapid antigen tests ? What is PCR test ??

 

What is Rapid antigen card test??

It detects by rad system SAES COV 2 VIRAL Protein

 It is a bed side test & therefore often used at hospitals & N homes particularly as “on Admission tests” for Covid 19 antigen (viral proteins) . Covid-19 Rapid Antigen Card - It detects SARS COV 2 Viral Proteins  by Immunochromatograpy Card for rapid detection of antigens from samples collected from samples collected from nasopharynx and nose.  The test card contains antibodies against    SARS COV 2 Viral Proteins.  It detects viral RNA with fair degree of accuracy by card test at bedside by 30 minutes. No need of costly machines like RT PCR test machine . There will be two bands like UPT card if she/he carries virus. The said test card is impregnated at factory with  contains antibodies against SARS COV 2 Viral Proteins  . Appearance of two bands implies antigen positivity  in nasopharynx / nasal cavity of the subject.

But limitation is this tets can’t detect disease Free State. When one is being discharged from Hospital after an attack of Covid-19 then we have to confirm her/his diseases-free state by RT PCR which is 100% sensitive.

Indications of Rapid Antigen Test ( RAT) : A) All women/men  preoperatively  B) All Gynae /Obstet new admissions C) Mass screening in a locality at low cost . But when someone is test card +ve he/she should be sent to either quarantine (if asymtomatic)  or Covid hospital (if symptomatic) .  Those who were in contact with her/him they also should be tested by Rapid card test. Till date few companies are manufacturing this test card in our countries  and we have to import from other courtiers. Admittedly it is low cost test very useful for mass screening.

What is PCR tets? PCR test is the best method and near 100% sensitive as opposed to 80-85% sensitive in card test as described above. There are of three kinds like :-1) Open  RT PCR=Many companies do it by kit.

2) CB NAAT 3) TRUE NAT.

It takes 24-48 hours to detect the antigen (Viral antigen) .

 

 

 

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