Testing for COVID-19 (nuclei acid test and antibody)

Testing for COVID-19

Testing for COVID-19. The Panther Fusion® SARS-CoV-2 Assay

There are currently two types of tests available for COVID-19. It is important to know the difference and the value of each test.  The first test is to check for active infection. That is called a NAAT test (nucleic acid test).  If you have symptoms of COVID-19 or you have been exposed to someone with confirmed case of COVID-19.  The nucleic acid test looks for fragments of the viral RNA. The test is run by quest labs but doesn’t actually perform it on the patients at the present time in Northern Virginia.  There are multiple centers in Northern Virginia that do perform the test.

If the test is positive you should pretty much assume that you have the disease because the false positivity rate is quite low.  If you test negative and you have the symptoms you should still isolate yourself and retest because it could be false negative. The reasons for false negativity of the COVID-19 NAAT is the inherent flaw of the test, the handling of the specimen, the location where it was obtained ( nasal, oral , nasopharyngeal) and the viral load.   You may not have enough of a viral load for detection initially and that is why subsequent repeat test may turn positive. So if you initially test negative and you have symptoms, the test should be repeated. The tests are not FDA approved.  The tests have to undergo certain rigor and pass certain standards to be FDA approved and none of them have the longevity required for FDA approval. So the FDA has created a category called Emergency Use Authorization (EUA) for tests that have met certain reliability criteria . Three types of NAAT test that I know of have EUA approval (Aptima, Cobas and Panther Fusion).  I am sure there are others, ask if the test has EUA rating.  You should not rely on tests that don’t have at least EUA because then there is no scrutiny.

The antibody test looks for the Immunoglobulin G antibody.  If is a marker for immunity.  If you test positive for COVID-19 and then the IgG, it means you have acquired immunity. We don’t know how long this lasts. At this point, the CDC has a disclaimer about it.  Please read my post on (herd immunity and antibody testing) for more detailed answer.

Tomorrow I will post the guidelines from CDC on testing. Keep learning.



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