How do the tests for COVID-19 work?
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Lab Procedure, Issues Faced, Positive Or Negative Test
1) Lab Procedure
Step 1- Collecting Of SampleSwab is taken from inside nose or the back of the nose And. Send to lab for testing.
Step 2- PCR Process
a. RNA of virus is extracted from patient’s DNA and purified, An Enzyme reverse transcriptase, converts RNA into DNA.
b. The DNA is mixed with primers, Sections Of DNA design To Bind to Characteristic Parts of Virus DNA. With Repeatedly Cooling And Heating of DNA with these Primase And DNA building enzyme Making Millions Of Virulent DNA Copies
c. Fluorescent Dye Molecules Are Added Which Then Binding To Virulent DNA as it is also Copied, These Fluorescent Molecules helps in confirming presence of virus in the Sample.
STEP 3- Confirming Positive Or Negative Test
Positive test- If the fluorescent light Increased that confirms the presence of Virus DNA crossing certain threshold.
Negative Test- No DNA copies is made which means No Virulent DNA is present, Hence doesn’t cross the threshold
Issues faced-
1. High Demands Of Reagents leads to Delay In Test
2. It takes Few Hours To complete Test.
3. Sample Degradation And Contamination may affect the testing.
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There is another quicker test which only tests for presence of antibodies(ELISA test for AIDS also works on this same principle & hence always followed by a more rigorous 2nd test for confirmation in case of positive elisa test) but it is also more prone to wrong conclusions & that is why any such test is followed by above pcr test for confirmation.