Yes, it was already mentioned today in the update to parliament here. Apparently - as with other respiratory viral infections - if you don't get it really bad then you may not be immune. That's a pretty fine line there. This would explain some of the more puzzling positive / negative / positive test sequences.
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."
"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.
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.
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.
You beat the infection due to a skirmish between your 'standard' immune system and the virus infected cells. As soon as you get a full-on immune system response there is a change and some more long term effects come into play. Nature tends to be very efficient, engaging an expensive mechanism apparently leads to caching the knowledge so it can be recalled when required, but if the expense outweighs the cost of doing so then it stays on a one-off basis.
The longer you deal with biology the more impressive it all is.
There is the innate immune system, and the adaptive immune system. If I understand correctly pathogen specific antibodies are created by the adaptive immune system, so maybe if the innate deals with the virus quickly the adaptive is not triggered.
If your innate immune system beats it, does that mean you're effectively already "immune" and are unlikely to develop serious COVID-19 disease when you catch the virus again, or was it just luck?
I'm not referring the general concept. I've asked for a source that supported the claim that covid19 patients that "don't get it really bad" have been found to not get immune.
That was straight from a government hearing today here in NL, those usually don't come with conveniently linked sources but at the same time they tend not to have bullshit in them.
But do you have a source that backs up your baseless assertion? The world is tired of random guys online saying all type of nonsense and making all sorts of wild claims to then cower behind empty appeals to authority. I can just as easily claim that the pope said to me personally the exact opposite of what you're saying.
These people came out of hospital. I think they have been hit comparatively hard. I guess (!) we see some result of false-positive test results here, together with coinfection with influenca or even the common flu.
Hospital cases are all lower respiratory tract, but even just within that group there is huge variety. It starts from 'under observation' for a day, then goes through needed oxygen for a day or two, to progressively worse symptoms, cytokine storms, intubation, organ failure and finally death, from a couple of different causes, such as lung damage (the vast majority of the cases) or heart failure (1 in 5). It can reverse at any point during that trajectory, and can also go back-and-forth.
And the speed of onset, progression and severity can change dramatically from person to person.
Finally, in many cases of recovery there is apparently lasting damage.
So, young people have way less antibodies. Lots of stats also show people aged 0-19 have barely any test-confirmed infetions compared to older populations. I also read that for the first 7 days, the virus mostly stays in your throat with mild symptoms and only after that it goes to the lungs causing major issues.
Could it be that young people with strong immune systems easily fight the virus away within the first week?
Out of my keister I'd assume young people's innate immune response might often defeat the virus on it's own. By the time the adaptive immune system kicks in the war is over.