Here’s an uneasy answer
Broadly, two methods of tests are available for SARS-CoV-2: molecular, which looks for the presence of the virus or its genetic material in the sample of nasal mucous or saliva, and serological, which looks for the presence of antibodies in the blood.
The first one is based on a routine lab technique, reverse transcription polymerase chain reaction (RT-PCR), which amplifies the minuscule amount genetic material in a pathogen and helps identify it. The technique has to be customised as per the disease by using primers, or short nucleic acid sequences, specific to the pathogen’s genetic material. Typically, the procedure involves sticking a swab, similar to an earbud, but uses nylon instead of cotton, deep into the nose or throat, retrieving mucous sample, placing the swab in buffer solution to transport and isolate the virus, replicating its genetic material using chemicals or reagents like primers, enzymes and nucleotides, and then detecting it with fluorescent probes. Once the sample reaches lab, the entire process takes six hours (see 'Not so easy hunt',
The serological test kit, on the other hand, is simpler and portable, just like a pregnancy test kit, and can give results in 20-30 minutes. It is also cheaper—in India, a rapid antibody test costs about `400 compared to RT-PCR that costs `4,500. Based on a drop of blood, these test strips look for antibodies that are produced as a natural defence mechanism of the body when exposed to a pathogen. Thus, it not only helps find out those who were infected and subsequently recovered, it also helps
BOTH THE TESTS HAVE LIMITATIONS. FOR ONE, NONE OF THEM CAN TELL FOR SURE IF A PERSON IS COVID-19POSITIVE OR NEGATIVE. THESE FLAWS ARE NOW MORE PRONOUNCED BECAUSE OF THE HASTE WITH WHICH THE TESTING MACHINES AND KITS ARE BEING DEVELOPED, REVIWED AND APPROVED
identify asymptomatic patients who could have silently spread the infection.
But the effectiveness of any medical test depends on accurate diagnosis. This is assessed in two ways: specificity and sensitivity. Sensitivity is the ability of a test to correctly identify those with the disease (true positive), whereas specificity is the ability of the test to identify those without the disease (true negative). This is crucial as the disease would continue to spread if a positive patient is reported negative. If someone tests false positive, then he or she would have to go through needless treatment and duress. Both the tests are mired in these specificity and sensitivity issues. This limitation is now getting more pronounced because of the haste with which the testing tools and kits are being developed and approved. Besides, never before has the world seen such a huge demand for tests. This has overwhelmed developers as well as suppliers, triggering shortages everywhere.