[_wldu]

Researchers are finding that COVID-19 testing has roughly 33% false negatives.

https://www.wsj.com/articles/questions-about-accuracy-of-cor...

The LabCorp test is not FDA cleared or approved and is being used under an emergency act.

"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."

The Quest test is not FDA approved either: https://www.questdiagnostics.com/dms/Documents/covid-19/SARS...

"It is possible for this test to give a negative result that is incorrect (false negative) in some people with COVID-19. This means that you could possibly still have COVID-19 even though the test is negative."

Due to this, it's hard to trust test results. It's a best effort and not perfect.

[vinniejames]

What are the false positives rate?

This would affect death rate calculations

[Symmetry]

A PCR will generally have around a 99% sensitivity and a 95% specificity. That depends on things like the nasal swab going all the way to the back in a deeply uncomfortable way and if they only get the front of the nasal cavity (with Covid-19 in particular) it might be just a 95% sensitivity.

Antibody tests will generally have a much lower sensitivity but can detect whether you had the virus in the past.

[_wldu]

Dr. Fauci said the only thing you can count on are positive test results, so I would assume false positives are much more rare, but I'm not qualified to say. I do think it's safe to discount a negative test result, especially if you also test negative for flu A/B but still have flu like symptoms and difficulty breathing. Hopefully soon, antibody testing will be available and much more accurate.