If as I have read, that C P is most effective during the first three days, I suspect that doctors may be reluctant to administer it to folks who have been laid up say for 9 days and more. With this EUA today, I suspect that folks are inquiring of the doctors of their loved ones, "when are you going to start the C P treatment?" Only to be told that their loved one is passed the point of it being an effective treatment. The next question would then be "Are there any other options available?"
The answer would be clinical trials which, may then see participants being signed up at a faster rate than at present.