Thread by @Laurie_Garrett

None of the studies of #COVID19 treatment use of serum taken from survivors (aka convalescent serum therapy) show positive results, & @US_FDA has stopped approving its use.
But @realDonaldTrump will announce a breakthru tonight.
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thehill.com/homenews/admin…

2/ This not new, just his insistence it works. No coincidence, I'm sure, that it comes on the eve of the #RNCConvention2020 putting a positive spin on the #COVID19 crisis.
Here's what we know about convalescent therapy so far.
It might work: MORE
statnews.com/2020/08/13/lar…

3/
But on Aug 19 the @NIH & @US_FDA urged a hold on use of the treatments, citing lack of clear evidence that it is beneficial. And it is not risk-free.
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nytimes.com/2020/08/19/us/…

4/ One study shows effective plasma therapy must be given very soon (before seroconversion) and must involve high titer NAbs. Otherwise, the dilution effect of 10-20 fold when plasma is given to a NAb positive patient makes it all rather pointless.
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medrxiv.org/content/10.110…

5/
A Texas study similarly found less mortality among plasma transfusion recipients IF they received treatment early in the disease process.
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ajp.amjpathol.org/article/S0002-…

6/
The largest plasma transfusion #COVID19 study, from the Mayo Clinic, treated 35,522 patients, seeing a small mortality benefit. Again, positive effects were only seen if patients were treated very early -- like, 3 days after seroconversion.
medrxiv.org/content/10.110…