CDC reported half of the anti-body tests were inaccurate
by Wolfetone (2020-06-20 13:54:38)

In reply to: Here's a question on the testing? If we find that it is true  posted by DomerJon

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About a month ago.I don't know if there has been any improvement
since then. The feeling amongst some medical men is that if you have
anti-bodies then it won't come back. Others say there is no immunity
and it can come back again and again like the regular flu. Who knows?

I posted about this awhile ago. The test is accurate
by dulac89  (2020-06-21 18:09:14)     cannot delete  |  Edit  |  Return to Board  |  Ignore Poster   |   Highlight Poster  |   Reply to Post

But when applied to a disease with low prevalence even going from 99 to 98% sensitivity decreases positive predictive value considerably

For all these tests a negative is for all practical purposes a true negative. But until disease prevalence increases PPV will remain lower
Thanks. You can/can't /who knows, get Corvid-19 again?
by Wolfetone  (2020-06-22 09:55:35)     cannot delete  |  Edit  |  Return to Board  |  Ignore Poster   |   Highlight Poster  |   Reply to Post

Some feel if you have antibodies and have recovered you are safe.
What is your opinion?
It’s not really an issue of test accuracy
by carroll2005  (2020-06-20 15:07:09)     cannot delete  |  Edit  |  Return to Board  |  Ignore Poster   |   Highlight Poster  |   Reply to Post

It’s an issue of people not understanding statistics, prevalence, and pre-test probability.

Basically - the prevalence in most communities makes pre-test probability extremely low, so even a test with 99% sensitivity/specificity will end up having a false positive nearly as often as a true positive.

Extreme example of the statistics concept: you have a pregnancy test that is 99.9% accurate. But you are administering it to a man. Pre-test probability of a true positive test is 0, so it doesn’t matter how accurate your test is.