Kim also said patients had likely “relapsed” rather than been re-infected.
False test results could also be at fault, other experts said, or remnants of the virus could still be in patients’ systems but not be infectious or of danger to the host or others.
“There are different interpretations and many variables,” ...
https://www.questdiagnostics.com/dms/Documents/covid-19/SARS...
"Is this test FDA-approved or cleared?
No. This test is not yet approved or cleared or authorized by the United States Food and Drug Administration (FDA). When there are no FDA-approved or cleared tests available, and other criteria are met, FDA can make tests available under an emergency access mechanism called an Emergency Use Authorization. Quest Diagnostics is working with FDA to obtain Emergency Use Authorization."
And the tests that are authorized for emergency use are not FDA cleared or approved.
"Testing was performed using the cobas(R) SARS-CoV-2 test. This test was developed and its performance characteristics determined by LabCorp Laboratories. This test has not been FDA cleared or approved. This test has been authorized by FDA under an Emergency Use Authorization (EUA). This test is only authorized for the duration of time the declaration that circumstances exist justifying the authorization of the emergency use of in vitro diagnostic tests for detection of SARS-CoV-2 virus and/or diagnosis of COVID-19 infection under section 564(b)(1) of the Act, 21 U.S.C. 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner."
I'm an infectious disease doctor and would like to point out an important factor in diagnosing this infection (and all respiratory pathogens that use nucleic acid probes for specimen collection). This is of particular concern now that China has transitioned to a much more problematic clinical diagnosis based more on clinical symptoms than PCR testing.
While it may seem trivial how a health care worker jams a swab in to someone's throat or nose, technique is important. If anterior naries (front of nose) swabs or side of mouth swabs are done, rather than the true posterior nasopharynx or oropharangeal swabs, the sensitivity drops dramatically.
We have shown this to be true repeatedly with diagnosis of influenza and respiratory pathogens, and I am disappointed that it has not been mentioned more in discussions about the PCR tests, missing the diagnosis in people who are positive and negative then positive again.
We often see people admitted from the ER with the perhaps carelessly collected flu test who miraculously are flu positive by the time they are admitted. Like so many cultures and diagnostics in infectious diseases, specimen collection and handling is critical.
I warn my patients about the unpleasantness of a nasopharangeal swab and jokingly tell them that if it doesn't cause a wincy-face reaction we haven't collected specimens from where the viruses reside.
[1] - http://www.microbe.tv/twiv/twiv-588/; at about 1 hour and 38 minutes in
RT-PCR tests can only test for the presence of viral RNA in the sample collected. They cannot tell you the viability of the viral particles, they cannot tell you if you going to get sicker, or going to get better the next day. We don't even fully understand the relationship between vRNA detection and contagiousness. And all of those unknowns are outside of the scope of the test.
Even in normal times, these tests can only be used to determine if genetic material exists (and sometimes the quantity if the collection mechanism and processing are controlled enough). It must be left up to clinicians to interpret these results.
The current protocol is to wait for 2 consecutive negatives 24 hours apart to call someone virus free. That's a protocol created by clinicians in a time of extreme pressure and need based on empirical measurements and prior body of knowledge.
A 510k cleared COVID test would have most of the same issues because the problem isn't strictly that the tests can't reliability detect viral particles, the problem is that we don't know what actually constitutes "cured".
[1] https://www.wsj.com/articles/questions-about-accuracy-of-cor...