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
Spike versus nucleoprotein for serological testing - I guess we might have a winner (I declare I have a COI)
Oops. When antibody tests assay antibodies that are not neutralizing, as several companies currently do w/ Measuring the N-protein instead of the RBD protein; it's even more complicated than that
NYT mentions work I helped with, finding that antibodies decline, but time to N-antibody seronegativity ~ 195 days. Could mean we underestimate cumulative prevalence, and more so the later it gets.
3) Immunity cont’d: Antibodies go high w primary infection and wane quickly. We know this. Yet it led to massive confusion/concern. People like luckily chimed in to remind that this is normal and wrote a nice about it 7/
Sorry for the long thread but immunology is complicated! Huge thanks to , Fiona Havers, for their patience and expertise, and for sharing his story. Please read the full article
Falling antibody levels to the coronavirus do not necessarily mean that you're losing immunity. Here's why. 
Your Coronavirus Antibodies Are Disappearing. Should You Care?
Declining antibody levels do not mean less immunity, experts say. Besides, two widely used tests may detect the wrong antibodies.
via . As described here, I had neg Ab testing 2 mos after having COVID. Thanks to ⁦⁩ for this interesting article proposing why this may the case for some
Mindblowing. The two main antibody tests (Abbott & Roche) are not testing for the right COVID antibodies. "The most powerful antibodies recognize the coronavirus’s spike protein [...] the Roche & Abbott tests look for a protein called the nucleocapsid."
Declining antibodies to #COVID as shown by many commercial tests, don’t necessarily mean declining #immunity, as many are designed to detect a subtype of antibodies that doesn’t confer immunity & may wane even faster than those that can destroy the virus.
Another great piece by ⁦⁩ helping the public decipher what we know and don’t know abt immunity and Ab tests. Spoiler: the tests aren’t great, may not be looking for right part of the virus, and so we must all act as if we aren’t immune
“Even if their antibodies wane below the limits of detection of our instruments, it doesn’t mean their ‘memory’ is gone”
Your #coronavirus Antibodies Are Disappearing: Should You Care? via
Your Coronavirus Antibodies Are Disappearing. Should You Care?
Why does this matter? Many of the commercial platforms around the country are only measuring antibodies against the NC protein, which appear faster but are not the “business end” of neutralization activity against the virus, like the S-RBD antibodies are.