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You know people -- maybe you're one of them -- who were sick with Covid, but tested negative for antibodies. Why would that be?
Blame the tests. They miss antibodies at low levels or are even looking for the wrong kind. 1/x https://www.nytimes.com/2020/07/26/health/coronvirus-antibody-tests.html
Blame the tests. They miss antibodies at low levels or are even looking for the wrong kind. 1/x https://www.nytimes.com/2020/07/26/health/coronvirus-antibody-tests.html
When you encounter a virus, antibodies to tackle that virus take many days to come up, grow in numbers, and after their work is done, drop to low levels. This is perfectly normal and doesn't mean you will be reinfected, as I reported a few days ago. 2/x https://www.nytimes.com/2020/07/22/health/covid-antibodies-herd-immunity.html
In fact, every drop of your blood has a teeny amount of antibodies to every pathogen your body has ever had to fight. Isn’t that the coolest thing you’ve ever heard? 3/x
Timing is key: If you take an antibody test too soon after the PCR (or at the same time), you may get a negative result. But if you take it too late—after the levels drop—you may again get a negative result. That doesn’t mean you have no immune memory 4/x
Even a low level of antibodies that the tests can’t detect can be quickly ramped up – within hours – if you’re exposed to the virus again. With every exposure, this response grows stronger and stronger. 5/x
A very few people may not make antibodies at all. But they will still have immunity from T cells, which can recognize, remember and kill viruses. Again, how cool is the immune system? 6/x https://www.nytimes.com/2020/07/22/health/covid-antibodies-herd-immunity.html
This blew my mind: *several* tests — including ones made by @Roche and @AbbottNews, used by Quest/ @LabCorp -- test for antibodies to the nucleocapsid (N) rather than to the receptor binding domain (RBD) of the spike (S) protein, or the “business” end of the virus. Why? 7/x
The N protein is plentiful, so antibodies to it produce an early bright signal—which is great for test makers in terms of showing a high sensitivity. But some reports now suggest N antibodies may also wane faster than antibodies to the spike or RBD. 8/x
Even if that turns out not to be true – most of the time N and S antibodies have similar kinetics – it is just confusing for companies to be testing for antibodies that have little to do with immunity. 9/x
So… bottom line, if you had confirmed Covid (ie, not if you just thought you had it), chances are pretty good that you have some protection from the virus, *even* if you got a negative antibody test. 10/x
Sorry for the long thread but immunology is complicated!
Huge thanks to @michaelmina_lab, Fiona Havers, @VirusesImmunity @angie_rasmussen for their patience and expertise, and @JBerz_MD for sharing his story.
Please read the full article: https://www.nytimes.com/2020/07/26/health/coronvirus-antibody-tests.html
Huge thanks to @michaelmina_lab, Fiona Havers, @VirusesImmunity @angie_rasmussen for their patience and expertise, and @JBerz_MD for sharing his story.
Please read the full article: https://www.nytimes.com/2020/07/26/health/coronvirus-antibody-tests.html
