Fully agree that a human challenge trial *would not* have resulted in an authorized/approved vaccine any sooner.
Disagree that every smart person was recommending a human challenge trial to speed up the approval process. 1/
Disagree that every smart person was recommending a human challenge trial to speed up the approval process. 1/
https://twitter.com/notdred/status/1333555525880049664
It is not a simple undertaking to establish a human challenge model, particularly with a novel virus for which the pathophysiology is not well-understood and where a targeted therapeutic is not available for what could be a lethal disease. 2/
Safety is obviously a major issue to be worked out, and this is tightly linked to ethical considerations. Beyond this, it takes time to determine the baseline infection/disease parameters that you hope to modify with the vaccine. 3/ thelancet.com/journals/lanin…
Safety considerations would argue for use of an attenuated strain. But if the goal is to use the model for licensure, then you want to mirror the disease to the greatest degree possible. A difficult balance for a virus we don't fully understand, and again, time is against us. 4/
These are just a few of the issues that would need to be worked out. But most importantly, no regulatory authority would license a vaccine on the basis of human challenge in the midst of a raging pandemic in which it's easy to accrue cases, ref Pfizer & Moderna trials. 5/
Having said this, human challenge trials can play a very important role in vaccine development if the safety and ethical considerations can be worked out. 6/
https://twitter.com/rvenkayya/status/1326876448100126720?s=20
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