1/ THREAD. So this is FASCINATING.

After a life-threatening case of #covid19, and more than a month after shot #2 of the #COVID19Vaccine, I’m barely positive for antibodies.https://abs.twimg.com/emoji/v2/... draggable="false" alt="👇" title="Rückhand Zeigefinger nach unten" aria-label="Emoji: Rückhand Zeigefinger nach unten">https://abs.twimg.com/emoji/v2/... draggable="false" alt="👇" title="Rückhand Zeigefinger nach unten" aria-label="Emoji: Rückhand Zeigefinger nach unten">https://abs.twimg.com/emoji/v2/... draggable="false" alt="👇" title="Rückhand Zeigefinger nach unten" aria-label="Emoji: Rückhand Zeigefinger nach unten">

In this thread, some background and a few thoughts.

#covid #coronavirus

2/ As some of you might recall, I was hospitalized from 3/16/20-4/1/20 at @nyulangone with a critical case of #covid19, spending almost a week on a ventilator.

In 6/20 and 9/20, I tested positive for #covid antibodies, in decreasing amounts — 4.3 and 3.2:

3/ In 11/20, my last #covid19 antibody test before this one, I was still positive, but not strongly so — titer of 2.3, where above 1.4 is positive.

4/ Last month, I got the #COVID19Vaccine of @pfizer, second shot on 3/22 — a month ago today. So I’m now fully #vaccinated https://abs.twimg.com/hashflags... draggable="false" alt=""> (yay).

#covid #covid19 #appellatetwitter

5/ For my pulmonologist visit yesterday, they did blood work, including a #covid19 antibody test — and as noted above, I was barely positive (1.5), despite my having had Covid AND being fully #vaccinated https://abs.twimg.com/hashflags... draggable="false" alt="">.

What’s the deal with that???

#covid #coronavirus

6/ My guess (as a layperson who has done some reading, NOT a doctor, biologist, or public health expert): the IGG antibody test I got yesterday focuses on different antibodies than those elicited by @pfizer’s mRNA vaccine.

#covid #covid19 #coronavirus

7/ As discussed in this article, for example, the mRNA vaccines and natural infection give rise to different antibodies (spike protein vs. nucleocapsid, respectively).

https://bit.ly/3nf6k7c ">https://bit.ly/3nf6k7c&q... #covid #covid19 #coronavirus #COVID19Vaccine #COVID19Vaccines

8/ If I’m correct, then maybe this 1.5 reading for my #covid19 antibodies means that I STILL have antibodies from my natural infection, more than one year after my original illness (i.e., this reading does NOT reflect the antibodies from my #vaccination).

9/ This could also explain why @CDCgov does NOT suggest getting an antibody test after getting the vaccine to assess immunity. The test might be negative (or barely positive like mine), but that does NOT mean the vaccine didn’t work. https://bit.ly/2QsnXnP ">https://bit.ly/2QsnXnP&q...

10/ Again, I’m not a doctor. Cc’ing folks who might actually know about this stuff: @florian_krammer @VirusesImmunity @mjmull @leorahorwitzmd @DrTomFrieden @apoorva_nyc.

11/ I expected my #covid19 antibodies to be through the roof, after natural infection AND full vaccination; instead, they’re modest. But maybe it’s bc of different antibodies?

I shouldn’t be worried about the low titer (1.5 where >1.4 is positive), should I?