Thread by @AndrewNoymer

Convalescent serum: the new hydroxychloroquine.

Convalescent serum has a long and successful history in fighting disease.

But that doesn't mean that it will necessarily succeed for *any* disease.

It needs to be studied better before make any all-in bets.

The reasons convalescent serum may work are many, but it boils down to this: it has worked for other diseases, ex. measles [before the vaccine].

But there are also reasons why it might NOT work. Many, in fact.

So we need to *study* it.

There are reasons why convalescent serum might NOT work. Many, in fact.

So we need to *study* it. We can't just say "well, it must work, theoretically".

The slagheap of ideas that "must" work in principle, but which don't work in practice, is humongous.

I love the idea of using convalescent serum in the C-19 fight — if it works.

Here are 2 reasons among many, why we need to be cautious.

1st, some evidence that by time people diagnosed, already have an antibody response. Convalescent serum may have marginal effect in such case.

2nd:

Biggest success of measles convalescent serum was in *prophylaxis*, *not* treatment. [And for coadministration with the early measles vaccines, but that's a different story.]

Given the magnitude of the pandemic, use as prophylaxis won't be practical.

continues...

cont'd.

And given all the testing problems, +testing delays, that we *still* have in the US of A...

...I don't see it as being practical as a therapy, in which it needs to be administered early.

Where the rubber meets the road, I very much doubt convalescnet serum will matter.